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Error inflating class ImageButton Stops app from starting

My app fails to start because of Error inflating class ImageButton, Because of this the phone says "app has stopped" Etc.
I am using firebase test lab to debug the problem
the Errors occur on samsung devices specifically A20, s7 Edge , s7(tested with firebase same problem)
I am new to android and have tried many solutions from google and SO none have worked sofar
Here is the error report on firebase
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smartpractice.smartpracticesmartapp/com.smartpractice.myapplication.MainActivity}: android.view.InflateException: Binary XML file line #117: Binary XML file line #117: Error inflating class ImageButton
FATAL EXCEPTION: main
Process: com.smartpractice.smartpracticesmartapp, PID: 26921
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.smartpractice.smartpracticesmartapp/com.smartpractice.myapplication.MainActivity}: android.view.InflateException: Binary XML file line #117: Binary XML file line #117: Error inflating class ImageButton
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3253)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3349)
at android.app.ActivityThread.access$1100(ActivityThread.java:221)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: android.view.InflateException: Binary XML file line #117: Binary XML file line #117: Error inflating class ImageButton
at android.view.LayoutInflater.inflate(LayoutInflater.java:551)
at android.view.LayoutInflater.inflate(LayoutInflater.java:429)
at android.view.LayoutInflater.inflate(LayoutInflater.java:380)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:469)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:140)
at com.smartpractice.myapplication.MainActivity.onCreate(MainActivity.java:14)
at android.app.Activity.performCreate(Activity.java:6876)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3206)
... 9 more
Caused by: android.view.InflateException: Binary XML file line #117: Error inflating class ImageButton
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:794)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:716)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:847)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:810)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:855)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:810)
at android.view.LayoutInflater.inflate(LayoutInflater.java:527)
... 17 more
Caused by: android.content.res.Resources$NotFoundException: Resource ID #0x7f070089
at android.content.res.Resources.getValue(Resources.java:2558)
at androidx.appcompat.widget.AppCompatDrawableManager.loadDrawableFromDelegates(AppCompatDrawableManager.java:331)
at androidx.appcompat.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:198)
at androidx.appcompat.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:191)
at androidx.appcompat.content.res.AppCompatResources.getDrawable(AppCompatResources.java:102)
at androidx.appcompat.widget.AppCompatImageHelper.loadFromAttributes(AppCompatImageHelper.java:59)
at androidx.appcompat.widget.AppCompatImageButton.<init>(AppCompatImageButton.java:79)
at androidx.appcompat.widget.AppCompatImageButton.<init>(AppCompatImageButton.java:69)
at androidx.appcompat.app.AppCompatViewInflater.createImageButton(AppCompatViewInflater.java:202)
at androidx.appcompat.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:122)
at androidx.appcompat.app.AppCompatDelegateImpl.createView(AppCompatDelegateImpl.java:1266)
at androidx.appcompat.app.AppCompatDelegateImpl.onCreateView(AppCompatDelegateImpl.java:1316)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:758)
Here is the XML
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/relativeLayout4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/ic_launcher_background"
tools:context=".MainActivity">
<com.google.android.flexbox.FlexboxLayout
android:id="#+id/flexboxLayout"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
app:alignContent="stretch"
app:alignItems="stretch"
app:flexWrap="wrap"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.863"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/guideline7">
<TextView
android:id="#+id/textView"
android:layout_width="match_parent"
android:layout_height="48dp"
android:fontFamily="#font/nunito"
android:gravity="center_horizontal"
android:text="#string/welcome_to_smartpractice"
android:textSize="24sp"
app:fontFamily="#font/nunito"
app:layout_alignSelf="baseline"
tools:layout_editor_absoluteY="100dp"
tools:targetApi="jelly_bean" />
<TextView
android:id="#+id/textView7"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/colorPrimaryDark"
android:gravity="center_horizontal|fill_vertical"
android:text="#string/docsharesmart"
android:textColor="#color/ic_launcher_background"
app:layout_alignSelf="flex_end"
tools:layout_editor_absoluteY="16dp" />
</com.google.android.flexbox.FlexboxLayout>
<com.google.android.flexbox.FlexboxLayout
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="4dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
app:alignContent="center"
app:alignItems="stretch"
app:flexDirection="row"
app:flexWrap="nowrap"
app:justifyContent="space_between"
app:layout_constraintBottom_toTopOf="#+id/guideline7"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<ImageView
android:id="#+id/imageView3"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="#string/logo1"
app:layout_alignSelf="center"
app:srcCompat="#drawable/smartpractice_logo_02"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="-46dp" />
<ImageButton
android:id="#+id/LoginScreen"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#null"
android:contentDescription="#string/loginscreen"
app:layout_alignSelf="center"
app:layout_wrapBefore="false"
app:srcCompat="#drawable/ic_more_vert_black_24dp"
tools:layout_editor_absoluteX="248dp"
tools:layout_editor_absoluteY="134dp" />
</com.google.android.flexbox.FlexboxLayout>
<com.google.android.flexbox.FlexboxLayout
android:id="#+id/flexboxLayout2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
app:alignContent="stretch"
app:alignItems="stretch"
app:flexWrap="wrap"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/flexboxLayout"
app:layout_constraintVertical_bias="0.146">
Here is line 117 from the error
<ImageButton
android:id="#+id/UploadButton"
android:layout_width="300dp"
android:layout_height="209dp"
android:background="#android:color/transparent"
app:layout_constraintTop_toBottomOf="#+id/flexboxLayout"
app:srcCompat="#drawable/upload_files_upload"
android:contentDescription="#string/todo" />
</com.google.android.flexbox.FlexboxLayout>
<androidx.constraintlayout.widget.Guideline
android:id="#+id/guideline7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_begin="185dp" />
</androidx.constraintlayout.widget.ConstraintLayout>

It means upload_files_upload is not found in drawble folder, well this can be a case, where your file may present in drawable-24 but not in drawble folder, in that case this problem still arise. The point is your file must be in all drawble folder.

The reason for your error is that the upload_files_upload is not in your drawable folder :
<ImageButton
android:id="#+id/UploadButton"
android:layout_width="300dp"
android:layout_height="209dp"
android:background="#android:color/transparent"
app:layout_constraintTop_toBottomOf="#+id/flexboxLayout"
app:srcCompat="#drawable/upload_files_upload"// this line
android:contentDescription="#string/todo" />

I have solved The Issue I changed app:srcCompat="#drawable/upload_files_upload"// to android:src="#drawable/upload_files_upload"
So the problem was by app:srcCompat I changed it to Android:src and it works fine now

My app is not working on Marshmallow and below but min sdk is 21. How to resolve?

Click here for gradebuild app file
Min SDK screenshot details:Minsdk is set to 21 & TargetSDK is set to 27
I am a beginner in Android Studio and this is my first app.
Click here for Logcat: Logcat
This is the activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="#ffffff"
tools:context=".MainActivity"
tools:layout_editor_absoluteY="25dp"
tools:layout_width="match_parent">
<ImageButton
android:id="#+id/cgpa"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:background="#ffffff"
android:onClick="clickcgpa"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/cal"
android:contentDescription="#string/todo4" />
<ImageButton
android:id="#+id/cal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:background="#ffffff"
android:onClick="clickcal"
app:layout_constraintEnd_toStartOf="#+id/club"
app:layout_constraintStart_toEndOf="#+id/map"
app:layout_constraintTop_toTopOf="#+id/club"
app:srcCompat="#drawable/calender"
android:contentDescription="#string/todo3" />
<ImageButton
android:id="#+id/map"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignTop="#+id/cgpa"
android:layout_marginStart="3dp"
android:background="#ffffff"
android:onClick="clickmap"
app:layout_constraintEnd_toStartOf="#+id/calendar"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/calendar"
app:srcCompat="#drawable/marker"
android:contentDescription="#string/todo1" />
<TextView
android:id="#+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="#+id/cgpa"
android:layout_marginEnd="9dp"
android:text="#string/cgpa_calculator"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/cgpa"
app:layout_constraintTop_toBottomOf="#+id/cgpa" />
<TextView
android:id="#+id/textView5"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginStart="16dp"
android:text="#string/campus_map"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="#+id/textView6"
app:layout_constraintStart_toStartOf="#+id/map"
app:layout_constraintTop_toBottomOf="#+id/map" />
<TextView
android:id="#+id/textView6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentTop="true"
android:layout_marginEnd="33dp"
android:gravity="center_vertical"
android:text="#string/Main"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/calendar"
app:layout_constraintTop_toBottomOf="#+id/calendar" />
<TextView
android:id="#+id/textView7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="18dp"
android:fontFamily="monospace"
android:text="#string/coming_soon"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
android:textColor="#777777"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView4" />
<ImageButton
android:id="#+id/club"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="234dp"
android:background="#ffffff"
android:onClick="clickclub"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/calendar"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/people2"
android:contentDescription="#string/todo2" />
<TextView
android:id="#+id/textView8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/club"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/club"
app:layout_constraintStart_toStartOf="#+id/club"
app:layout_constraintTop_toBottomOf="#+id/club" />
</android.support.constraint.ConstraintLayout>
This is activity_welcome.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000000"
tools:context=".Welcome">
<ImageView
android:id="#+id/imageView5"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/logomain" />
</android.support.constraint.ConstraintLayout>
And Manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.workingbros.ak.assist" android:versionCode="2">
<application
android:icon="#drawable/logomain1"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".CGPA"></activity>
<activity android:name=".MainActivity">
</activity>
<activity android:name=".Welcome">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Stack Trace:
04-12 23:25:46.153 30277-30277/com.workingbros.ak.assist E/Minikin: addFont failed to create font /system/fonts/NanumGothic.ttf
addFont failed to create font /system/fonts/DroidSansFallback.ttf
04-12 23:25:46.154 30277-30277/com.workingbros.ak.assist E/Minikin: addFont failed to create font /system/fonts/MTLmr3m.ttf
04-12 23:25:46.364 30277-30277/com.workingbros.ak.assist E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.workingbros.ak.assist, PID: 30277
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.workingbros.ak.assist/com.workingbros.ak.assist.MainActivity}: android.view.InflateException: Binary XML file line #13: Binary XML file line #13: Error inflating class ImageButton
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2560)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2626)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1475)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5740)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:766)
Caused by: android.view.InflateException: Binary XML file line #13: Binary XML file line #13: Error inflating class ImageButton
at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at android.view.LayoutInflater.inflate(LayoutInflater.java:374)
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287)
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139)
at com.workingbros.ak.assist.MainActivity.onCreate(MainActivity.java:15)
at android.app.Activity.performCreate(Activity.java:6543)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2513)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2626) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1475) 
at android.os.Handler.dispatchMessage(Handler.java:111) 
at android.os.Looper.loop(Looper.java:207) 
at android.app.ActivityThread.main(ActivityThread.java:5740) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:766) 
Caused by: android.view.InflateException: Binary XML file line #13: Error inflating class ImageButton
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:782)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139) 
at com.workingbros.ak.assist.MainActivity.onCreate(MainActivity.java:15) 
at android.app.Activity.performCreate(Activity.java:6543) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2513) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2626) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1475) 
at android.os.Handler.dispatchMessage(Handler.java:111) 
at android.os.Looper.loop(Looper.java:207) 
at android.app.ActivityThread.main(ActivityThread.java:5740) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:766) 
Caused by: android.content.res.Resources$NotFoundException: Resource ID #0x7f070054
at android.content.res.Resources.getValue(Resources.java:1552)
at android.support.v7.widget.AppCompatDrawableManager.loadDrawableFromDelegates(AppCompatDrawableManager.java:328)
at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:193)
at android.support.v7.widget.AppCompatDrawableManager.getDrawable(AppCompatDrawableManager.java:186)
at android.support.v7.content.res.AppCompatResources.getDrawable(AppCompatResources.java:100)
at android.support.v7.widget.AppCompatImageHelper.loadFromAttributes(AppCompatImageHelper.java:58)
at android.support.v7.widget.AppCompatImageButton.<init>(AppCompatImageButton.java:78)
at android.support.v7.widget.AppCompatImageButton.<init>(AppCompatImageButton.java:68)
at android.support.v7.app.AppCompatViewInflater.createImageButton(AppCompatViewInflater.java:201)
at android.support.v7.app.AppCompatViewInflater.createView(AppCompatViewInflater.java:121)
at android.support.v7.app.AppCompatDelegateImplV9.createView(AppCompatDelegateImplV9.java:1035)
at android.support.v7.app.AppCompatDelegateImplV9.onCreateView(AppCompatDelegateImplV9.java:1092)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:746)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704) 
at android.view.LayoutInflater.rInflate(LayoutInflater.java:835) 
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:515) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
at android.view.LayoutInflater.inflate(LayoutInflater.java:374) 
at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:287) 
at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:139) 
at com.workingbros.ak.assist.MainActivity.onCreate(MainActivity.java:15) 
at android.app.Activity.performCreate(Activity.java:6543) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1113) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2513) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2626) 
at android.app.ActivityThread.-wrap11(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1475) 
at android.os.Handler.dispatchMessage(Handler.java:111) 
at android.os.Looper.loop(Looper.java:207) 
at android.app.ActivityThread.main(ActivityThread.java:5740) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:905) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:766) 
MainActivity.java
package com.workingbros.ak.assist;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
ImageButton cgpa,cal,map,club;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cgpa= findViewById(R.id.cgpa);
map=findViewById(R.id.map);
club=findViewById(R.id.club);
cal=findViewById(R.id.cal);
}
public void clickcgpa(View v){
Intent main=new Intent(MainActivity.this,CGPA.class);
startActivity(main);
}
public void clickmap(View v)
{
Toast.makeText(this,"Coming Soon",Toast.LENGTH_SHORT).show();
}
public void clickclub(View v)
{
Toast.makeText(this,"Coming Soon",Toast.LENGTH_SHORT).show();
}
public void clickcal(View v)
{
Toast.makeText(this,"Coming Soon",Toast.LENGTH_SHORT).show();
}
}
Welcome.java
package com.workingbros.ak.assist;
import android.content.Intent;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class Welcome extends AppCompatActivity {
private static int SPLASH_TIME_OUT=1000;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_welcome);
new Handler().postDelayed(new Runnable(){
#Override
public void run(){
Intent homeIntent=new Intent(Welcome.this,MainActivity.class);
startActivity(homeIntent);
finish();
}
},SPLASH_TIME_OUT);
}
}
please tell me where is the error?
Compilation error after applying fix:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:compileDebugJavaWithJavac'.
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:100)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:70)
at org.gradle.api.internal.tasks.execution.OutputDirectoryCreatingTaskExecuter.execute(OutputDirectoryCreatingTaskExecuter.java:51)
at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:62)
at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:54)
at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:60)
at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:97)
at org.gradle.api.internal.tasks.execution.CleanupStaleOutputsExecuter.execute(CleanupStaleOutputsExecuter.java:87)
at org.gradle.api.internal.tasks.execution.ResolveTaskArtifactStateTaskExecuter.execute(ResolveTaskArtifactStateTaskExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:54)
at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:34)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker$1.run(DefaultTaskGraphExecuter.java:248)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:241)
at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:230)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.processTask(DefaultTaskPlanExecutor.java:123)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.access$200(DefaultTaskPlanExecutor.java:79)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:104)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:98)
at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.execute(DefaultTaskExecutionPlan.java:626)
at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.executeWithTask(DefaultTaskExecutionPlan.java:581)
at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.run(DefaultTaskPlanExecutor.java:98)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.gradle.api.internal.tasks.compile.CompilationFailedException: Compilation failed; see the compiler error output for details.
at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:50)
at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:35)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegateAndHandleErrors(NormalizingJavaCompiler.java:98)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:51)
at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:37)
at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:35)
at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:25)
at org.gradle.api.internal.tasks.compile.incremental.IncrementalCompilationFinalizer.execute(IncrementalCompilationFinalizer.java:39)
at org.gradle.api.internal.tasks.compile.incremental.IncrementalCompilationFinalizer.execute(IncrementalCompilationFinalizer.java:24)
at org.gradle.api.tasks.compile.JavaCompile.performCompilation(JavaCompile.java:207)
at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:133)
at com.android.build.gradle.tasks.factory.AndroidJavaCompile.compile(AndroidJavaCompile.java:125)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
at org.gradle.api.internal.project.taskfactory.IncrementalTaskAction.doExecute(IncrementalTaskAction.java:46)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39)
at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:26)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:121)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:110)
at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:92)
... 32 more

You have given constraints to map Imagebutton, textView6 TextView and club ImageButton with respect to calender id but as i can see in your activity_main.xml file there is no view having calender id. May be you have it earlier but after that you have changed it to cal id. so, you have to refer your view constraints with respect to cal instead of calender id. Because of wrong id you are getting inflating error.
I have modified your activity_main.xml as below. you can just copy and paste it in your code.
edited activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="#ffffff"
tools:context=".MainActivity"
tools:layout_editor_absoluteY="25dp"
tools:layout_width="match_parent">
<ImageButton
android:id="#+id/cgpa"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:background="#ffffff"
android:onClick="clickcgpa"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/cal"
android:contentDescription="#string/todo4" />
<ImageButton
android:id="#+id/cal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:background="#ffffff"
android:onClick="clickcal"
app:layout_constraintEnd_toStartOf="#+id/club"
app:layout_constraintStart_toEndOf="#+id/map"
app:layout_constraintTop_toTopOf="#+id/club"
app:srcCompat="#drawable/calender"
android:contentDescription="#string/todo3" />
<ImageButton
android:id="#+id/map"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignTop="#+id/cgpa"
android:layout_marginStart="3dp"
android:background="#ffffff"
android:onClick="clickmap"
app:layout_constraintEnd_toStartOf="#+id/cal"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/cal"
app:srcCompat="#drawable/marker"
android:contentDescription="#string/todo1" />
<TextView
android:id="#+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="#+id/cgpa"
android:layout_marginEnd="9dp"
android:text="#string/cgpa_calculator"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/cgpa"
app:layout_constraintTop_toBottomOf="#+id/cgpa" />
<TextView
android:id="#+id/textView5"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginStart="16dp"
android:text="#string/campus_map"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="#+id/textView6"
app:layout_constraintStart_toStartOf="#+id/map"
app:layout_constraintTop_toBottomOf="#+id/map" />
<TextView
android:id="#+id/textView6"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentTop="true"
android:layout_marginEnd="33dp"
android:gravity="center_vertical"
android:text="#string/Main"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/cal"
app:layout_constraintTop_toBottomOf="#+id/cal" />
<TextView
android:id="#+id/textView7"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="18dp"
android:fontFamily="monospace"
android:text="#string/coming_soon"
android:textAppearance="#style/TextAppearance.AppCompat.Body2"
android:textColor="#777777"
android:textSize="24sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView4" />
<ImageButton
android:id="#+id/club"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="234dp"
android:background="#ffffff"
android:onClick="clickclub"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/cal"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/people2"
android:contentDescription="#string/todo2" />
<TextView
android:id="#+id/textView8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/club"
android:textAlignment="center"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="#+id/club"
app:layout_constraintStart_toStartOf="#+id/club"
app:layout_constraintTop_toBottomOf="#+id/club" />
</android.support.constraint.ConstraintLayout>
And in future if you want to change any views id then i suggest you to change it from design section because it will ask you a option to change id at all places where you have used it. So, you don't need to update it manually at every place.
UPDATE
As i can see in your project code(Received in private chat) there is some images only in drawable-v24. So, this images are only comfortable with some versions as said here. So, you have to put your images in drawable folder also to make compatible your app in all the versions.
As i can see there is two images cal.png and people2.png in only drawable-v24 and not in drawable folder. so, simple copy and paste them into drawable folder and all will be ok. You can run your project on every devices having versions between your minsdk and targetsdk version.

Android crash on startingActivityForResult() [duplicate]

I keep getting a java.lang.NullPointerException when I try to use ScrollView in an activity.
The weird thing is that I've used the exact same Scrollview setup in other activities. And all of a sudden I'm getting errors. I've tried cleaning the project and rebuilding.
And I've tried the good old restart the program. I learned a lot about Null Pointer Exceptions today, but I haven't been able to figure out why I keep getting Rendering Problems.
This is the java.lang.NullPointerException that is thrown on the XML:
java.lang.NullPointerException
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:738)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:149)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:835)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:838)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:838)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:394)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:223)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:426)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:510)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:498)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:888)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:498)
at com.android.tools.idea.rendering.RenderTask.access$600(RenderTask.java:72)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:610)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderService.runRenderAction(RenderService.java:362)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:629)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:652)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1700(AndroidLayoutPreviewToolWindowManager.java:80)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7$1.run(AndroidLayoutPreviewToolWindowManager.java:594)
at com.intellij.openapi.progress.impl.CoreProgressManager$2.run(CoreProgressManager.java:152)
at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:452)
at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:402)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:54)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:137)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7.run(AndroidLayoutPreviewToolWindowManager.java:589)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
So, none of this is code that I wrote. So I dove into the stack trace and found this:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:715)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at com.mitchellpalermo.tutroubleshooting.ContactPage.onCreate(ContactPage.java:11)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Which points to line 11 on the Contact.java file. Which looks like this (I've put indicators around line 11) :
package com.mitchellpalermo.tutroubleshooting;
import android.app.Activity;
import android.os.Bundle;
public class Contact extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact); // line 11
}
}
I don't see a problem with line 11.
Now, I can't figure out what is wrong with my code. Between Rendering Problems and NullPointerExceptions, I can't figure out what is actually wrong with my code.
This is an example of XML in an activity in which the ScrollView doesn't throw any errors:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context="com.mitchellpalermo.tutroubleshooting.ComputerOrProjector">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="vertical">
<TextView
style="#style/HeaderStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/solutions"
android:textStyle="bold" />
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="15dp"
card_view:cardBackgroundColor="#FFFFFF"
card_view:cardCornerRadius="4dp"
card_view:cardElevation="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
style="#style/Solution"
android:text="#string/pc_v_fifth" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_first" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_second" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_third" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_fourth" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
</LinearLayout>
</android.support.v7.widget.CardView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
style="#style/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:onClick="sendEmail"
android:text="#string/fixed"
android:textStyle="bold" />
<Button
style="#style/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:onClick="notFixedButton"
android:text="#string/not_fixed"
android:textStyle="bold" />
</LinearLayout>
</LinearLayout>
</ScrollView>
And here is the activity in which I receive errors:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:fillViewport="false">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
style="#style/HeaderStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/still_not_fixed" />
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="15dp"
card_view:cardBackgroundColor="#FFFFFF"
card_view:cardCornerRadius="4dp"
card_view:cardElevation="5dp">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/hector" />
<view
android:layout_width="match_parent"
android:layout_height="2dp"
android:backgroundTint="#android:color/darker_gray" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/robert" />
<view
android:layout_width="match_parent"
android:layout_height="2dp"
android:backgroundTint="#android:color/darker_gray" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/mitch" />
</android.support.v7.widget.CardView>
</LinearLayout>
</ScrollView>
Any suggestions? And thank you so much in advance!

Change <view to <View, because view is not about empty view. It's for custom view defined through class attr, like below:
<view
android:layout_width="wrap_content"
android:layout_height="wrap_content"
class="com.your.package.YourCustomView" />
And you got
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
because of LayoutInflater tries to parse class attr:
LayoutInflater source code
//...
View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
boolean ignoreThemeAttr) {
if (name.equals("view")) { // line 724
name = attrs.getAttributeValue(null, "class"); // line 725
}
// Apply a theme wrapper, if allowed and one is specified.
if (!ignoreThemeAttr) {
final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
final int themeResId = ta.getResourceId(0, 0);
if (themeResId != 0) {
context = new ContextThemeWrapper(context, themeResId);
}
ta.recycle();
}
if (name.equals(TAG_1995)) { // line 738
// Let's party like it's 1995!
return new BlinkLayout(context, attrs);
}
//...
On line 724 it check that your tag is view and gets true
On line 725 it tries to get class through class attr and gets null
On line 738 it tries to check for blink tag and gets crash
Also, there is a curious thing, Android developers added Easter egg, you can try it:
<view
android:layout_width="wrap_content"
android:layout_height="wrap_content"
class="blink">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Some text" />
</view>

After 2 days I solved this problem use View instead of view
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#faf4f4"></View>

How to click on a SimpleCursorAdapter ListFragment item in Espresso?

Using a fragment that is initiated from the Activity view via xml:
<fragment
android:id="#+id/listconversations"
android:contentDescription="my list fragment"
android:name="com.example.ui.MyListFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
android:visibility="visible"
android:layout_below="#+id/linearLayout"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentBottom="true" />
That has a custom list adapter for the item row supported by a SimpleCursorAdapter:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/rl_row"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:clickable="true"
android:paddingLeft="8dp"
android:paddingRight="4dp"
android:paddingTop="8dp"
android:paddingBottom="4dp">
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/ib_contact_details"
android:src="#drawable/green_arrow"
android:background="#color/transparent"
android:clickable="true"
android:layout_marginLeft="16dp"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Somebody Else Senior"
android:paddingBottom="4dp"
android:id="#+id/tv_marker_title"
android:textColor="#color/black"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_toLeftOf="#+id/ib_contact_details"
android:layout_toStartOf="#+id/ib_contact_details" />
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="the conversation"
android:textColor="#color/black"
android:id="#+id/tv_message"
android:layout_below="#+id/tv_marker_title"
android:layout_alignLeft="#+id/tv_marker_title"
android:layout_alignStart="#+id/tv_marker_title"
android:layout_toLeftOf="#+id/ib_contact_details"
android:layout_toStartOf="#+id/ib_contact_details" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text=""
android:gravity="center_horizontal"
android:textColor="#color/gray_btn_bg_pressed_color"
android:id="#+id/tv_timestamp"
android:layout_below="#+id/tv_message"
android:layout_toLeftOf="#+id/ib_contact_details"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/tv_partnerserial"
android:textColor="#color/blue"
android:layout_alignParentLeft="true"
android:layout_toLeftOf="#+id/ib_contact_details"
android:visibility="invisible" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/tv_imageurl"
android:layout_alignParentLeft="true"
android:layout_toLeftOf="#+id/ib_contact_details"
android:visibility="invisible" />
</RelativeLayout>
When attempting to run the following espresso test on a ListFragment with a SimpleCursorAdapter and a custom listview row:
onData(allOf(is(instanceOf(ListFragment.class)))).check(matches(isDisplayed()));
onData(anything())
.inAdapterView(withId(R.id.listconversations))
.atPosition(0)
.perform(click());
The following error occurs:
Running tests
Test running started
android.support.test.espresso.PerformException: Error performing 'load adapter data' on view 'is assignable from class: class android.widget.AdapterView'.
at android.support.test.espresso.PerformException$Builder.build(PerformException.java:83)
at android.support.test.espresso.base.DefaultFailureHandler.getUserFriendlyError(DefaultFailureHandler.java:70)
at android.support.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:53)
at android.support.test.espresso.ViewInteraction.runSynchronouslyOnUiThread(ViewInteraction.java:185)
at android.support.test.espresso.ViewInteraction.doPerform(ViewInteraction.java:115)
at android.support.test.espresso.ViewInteraction.perform(ViewInteraction.java:87)
at android.support.test.espresso.DataInteraction.load(DataInteraction.java:151)
at android.support.test.espresso.DataInteraction.check(DataInteraction.java:141)
at com.example.TestMainActivity.shouldBeAbleToLaunchMainScreen(TestMainActivity.java:149)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at com.example.ActivityRule$1.evaluate(ActivityRule.java:101)
at org.junit.rules.RunRules.evaluate(RunRules.java:18)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:24)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at org.junit.runner.JUnitCore.run(JUnitCore.java:136)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:270)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1837)
Caused by: java.lang.RuntimeException: No data found matching: (is an instance of android.support.v4.app.ListFragment) contained values: <[Data: Row 0: {name:"Peter B.", lastlines:"just a message test", lastcontacted:"2015-11-12 12:14:47", image_url:"http://example.com/7618de72-2015-09-01 07:35:42-droid_test1.jpg", partnerserial:"261cc6", _id:76, } (class: android.content.ContentResolver$CursorWrapperInner) token: 0, Data: Row 1: {name:"Community Help", lastlines:"what's going on?", lastcontacted:"2015-10-06 17:58:20", image_url:"https://example.com/image.jpg", partnerserial:"bbb321de", _id:77, } ... token: 4]>
at android.support.test.espresso.action.AdapterDataLoaderAction.perform(AdapterDataLoaderAction.java:96)
at android.support.test.espresso.ViewInteraction$1.run(ViewInteraction.java:144)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:422)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
Finish
I also tried:
onData(allOf(is(instanceOf(SimpleCursorAdapter.class)))).check(matches(isDisplayed()));
But that didn't work either.

I could get onView to work with the following:
onView(allOf(withId(R.id.ib_contact_details), hasSibling(withText("Blah Blah"))))
.perform(click());

The simplest solution that I used was:
onData(CursorMatchers.withRowString("NAME", "hbhj"))
.perform(click());
Here,
NAME: Is the column of.
hbhj: Is the name displayed on the listview element.

NPE while inflating layout (Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference)

I keep getting a java.lang.NullPointerException when I try to use ScrollView in an activity.
The weird thing is that I've used the exact same Scrollview setup in other activities. And all of a sudden I'm getting errors. I've tried cleaning the project and rebuilding.
And I've tried the good old restart the program. I learned a lot about Null Pointer Exceptions today, but I haven't been able to figure out why I keep getting Rendering Problems.
This is the java.lang.NullPointerException that is thrown on the XML:
java.lang.NullPointerException
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:738)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:149)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:835)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:838)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:838)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:70)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:811)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
at android.view.LayoutInflater.inflate(LayoutInflater.java:394)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:223)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:426)
at com.android.ide.common.rendering.LayoutLibrary.createSession(LayoutLibrary.java:350)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:510)
at com.android.tools.idea.rendering.RenderTask$2.compute(RenderTask.java:498)
at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:888)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:498)
at com.android.tools.idea.rendering.RenderTask.access$600(RenderTask.java:72)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:610)
at com.android.tools.idea.rendering.RenderTask$3.call(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderService.runRenderAction(RenderService.java:362)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:607)
at com.android.tools.idea.rendering.RenderTask.render(RenderTask.java:629)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.doRender(AndroidLayoutPreviewToolWindowManager.java:652)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager.access$1700(AndroidLayoutPreviewToolWindowManager.java:80)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7$1.run(AndroidLayoutPreviewToolWindowManager.java:594)
at com.intellij.openapi.progress.impl.CoreProgressManager$2.run(CoreProgressManager.java:152)
at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:452)
at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:402)
at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:54)
at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:137)
at org.jetbrains.android.uipreview.AndroidLayoutPreviewToolWindowManager$7.run(AndroidLayoutPreviewToolWindowManager.java:589)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:320)
at com.intellij.util.ui.update.MergingUpdateQueue.execute(MergingUpdateQueue.java:310)
at com.intellij.util.ui.update.MergingUpdateQueue$2.run(MergingUpdateQueue.java:254)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:269)
at com.intellij.util.ui.update.MergingUpdateQueue.flush(MergingUpdateQueue.java:227)
at com.intellij.util.ui.update.MergingUpdateQueue.run(MergingUpdateQueue.java:217)
at com.intellij.util.concurrency.QueueProcessor.runSafely(QueueProcessor.java:238)
at com.intellij.util.Alarm$Request$1.run(Alarm.java:351)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
So, none of this is code that I wrote. So I dove into the stack trace and found this:
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:715)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at android.view.LayoutInflater.inflate(LayoutInflater.java:365)
at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:378)
at android.app.Activity.setContentView(Activity.java:2145)
at com.mitchellpalermo.tutroubleshooting.ContactPage.onCreate(ContactPage.java:11)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Which points to line 11 on the Contact.java file. Which looks like this (I've put indicators around line 11) :
package com.mitchellpalermo.tutroubleshooting;
import android.app.Activity;
import android.os.Bundle;
public class Contact extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact); // line 11
}
}
I don't see a problem with line 11.
Now, I can't figure out what is wrong with my code. Between Rendering Problems and NullPointerExceptions, I can't figure out what is actually wrong with my code.
This is an example of XML in an activity in which the ScrollView doesn't throw any errors:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context="com.mitchellpalermo.tutroubleshooting.ComputerOrProjector">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="vertical">
<TextView
style="#style/HeaderStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/solutions"
android:textStyle="bold" />
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="15dp"
card_view:cardBackgroundColor="#FFFFFF"
card_view:cardCornerRadius="4dp"
card_view:cardElevation="5dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
style="#style/Solution"
android:text="#string/pc_v_fifth" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_first" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_second" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_third" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
<TextView
style="#style/Solution"
android:text="#string/pc_v_fourth" />
<View
android:layout_width="match_parent"
android:layout_height="2dp"
android:background="#android:color/darker_gray" />
</LinearLayout>
</android.support.v7.widget.CardView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
style="#style/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:onClick="sendEmail"
android:text="#string/fixed"
android:textStyle="bold" />
<Button
style="#style/NextButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:onClick="notFixedButton"
android:text="#string/not_fixed"
android:textStyle="bold" />
</LinearLayout>
</LinearLayout>
</ScrollView>
And here is the activity in which I receive errors:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:fillViewport="false">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
style="#style/HeaderStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="#string/still_not_fixed" />
<!-- A CardView that contains a TextView -->
<android.support.v7.widget.CardView xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="15dp"
card_view:cardBackgroundColor="#FFFFFF"
card_view:cardCornerRadius="4dp"
card_view:cardElevation="5dp">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/hector" />
<view
android:layout_width="match_parent"
android:layout_height="2dp"
android:backgroundTint="#android:color/darker_gray" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/robert" />
<view
android:layout_width="match_parent"
android:layout_height="2dp"
android:backgroundTint="#android:color/darker_gray" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/mitch" />
</android.support.v7.widget.CardView>
</LinearLayout>
</ScrollView>
Any suggestions? And thank you so much in advance!

Change <view to <View, because view is not about empty view. It's for custom view defined through class attr, like below:
<view
android:layout_width="wrap_content"
android:layout_height="wrap_content"
class="com.your.package.YourCustomView" />
And you got
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
because of LayoutInflater tries to parse class attr:
LayoutInflater source code
//...
View createViewFromTag(View parent, String name, Context context, AttributeSet attrs,
boolean ignoreThemeAttr) {
if (name.equals("view")) { // line 724
name = attrs.getAttributeValue(null, "class"); // line 725
}
// Apply a theme wrapper, if allowed and one is specified.
if (!ignoreThemeAttr) {
final TypedArray ta = context.obtainStyledAttributes(attrs, ATTRS_THEME);
final int themeResId = ta.getResourceId(0, 0);
if (themeResId != 0) {
context = new ContextThemeWrapper(context, themeResId);
}
ta.recycle();
}
if (name.equals(TAG_1995)) { // line 738
// Let's party like it's 1995!
return new BlinkLayout(context, attrs);
}
//...
On line 724 it check that your tag is view and gets true
On line 725 it tries to get class through class attr and gets null
On line 738 it tries to check for blink tag and gets crash
Also, there is a curious thing, Android developers added Easter egg, you can try it:
<view
android:layout_width="wrap_content"
android:layout_height="wrap_content"
class="blink">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Some text" />
</view>

After 2 days I solved this problem use View instead of view
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="#faf4f4"></View>