Develop Reference

Application crashes upon new Activity

I know and I do understand that this question has been asked, but I can't seem to interpret it for my application. I am creating an application - using Android Studio - that opens a Activity (called 'About'). When a user clicks on the 'about button' on my MainActivity, it should launch the 'About' activity. However, when I test this out on my device, it says the app has stopped. And on my output panel, it says something about an error with my Manifest.xml file?
MainActivity:
package com.msp.supercarsounds;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void clickedAbout(View view) {
final int result = 1;
Intent AboutButtonClicked = new Intent (this, About.class);
AboutButtonClicked.putExtra("About", "MainActivity");
startActivityForResult(AboutButtonClicked, result);
}
}
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest
xmlns:android="http://schemas.android.com/apk/res/android"
package="com.msp.supercarsounds">
<uses-sdk android:minSdkVersion="17"
android:targetSdkVersion="22"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Thank you for your help and time!

You have to declare About activity
<activity android:name=".About">
</activity>
Add this below the </activity> tag of MainActivity

your second activity "about" is not added to manifest.xml add this under the mainactivity
<activity android:name=".about">/activity>

Unfortunately [yourapp], has stopped

I'm using intent method to make a simple app that takes you from main screen [with an enter button] to another screen which has three options. Code sourced online and seems to be error free, though my app crashes saying "Unfortunately [yourapp], has stopped" immediately after i press the button which is meant to take to the the other screen.
This is my first activity code:
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
}
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.enterBtn);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, HomeActivity.class);
startActivity(intent);
}
});
}
}`
And this is my landing screen's activity code:
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
public class HomeActivity extends Activity {
Button button;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
}
}
I'm really stuck with this issue and any help would be much appreciated. Many thanks in advance.

Every activity needs to be added in your manifest file under application tag. This seems to be the problem in your case.

Try to post you LogCat so that we might get some more information and if you have not yet added your Activity in the manifest, this is the way of adding it (Activities go under application tag)
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.southmp3"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".HomeActivity"
android:label="#string/app_name" >
</activity>
</application>
all the Activities should be going under the application tag

I had forgotten to register my new activity on the androidmanifest.xml file. That's what sorted my app crash issue.

Moving from one activity to another Activity in Android

I want to move from one activity to another (using virtual device). When I click on button to move, My emulator ones a dialog box showing unfortunately SMS1 has stopped working (SMS1 is my app name).
Can anybody help me in correcting my code?
MainActivity.java:
package com.example.sms1;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity implements OnClickListener
{
Button b1;
TextView tv1;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1 = (Button) findViewById(R.id.button1);
tv1 = (TextView) findViewById(R.id.textView1);
b1.setOnClickListener(this);
}
#Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public void onClick(View v)
{
// TODO Auto-generated method stub
Intent i = new Intent(getApplicationContext(),NextActivity.class);
startActivity(i);
setContentView(R.layout.avtivity_next);
}
}
Here is the NextActivity
package com.example.sms1;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
public class NextActivity extends Activity {
TextView tv1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.avtivity_next);
tv1 = (TextView) findViewById(R.id.textView1);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
Manifest.XML
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.sms1"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.sms1.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
NextActivityLayout
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".NextActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="next activity" />
</RelativeLayout>
MainActivity Layout
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/textView1"
android:layout_marginTop="80dp"
android:layout_toRightOf="#+id/textView1"
android:text="Button" />
</RelativeLayout>

First You have to use this code in MainActivity.java class
#Override
public void onClick(View v)
{
// TODO Auto-generated method stub
Intent i = new Intent(getApplicationContext(),NextActivity.class);
startActivity(i);
}
You can pass intent this way.
Second
add proper entry into manifest.xml file.
<activity android:name=".NextActivity" />
Now see what happens.

You haven't defined NextActivity in the AndroidManifest.xml file.
Add these lines in android manifest after</activity> tag. It should work.
<activity
android:name=".NextActivity" >
</activity>
final code will be
<application
android:allowBackup="true"
android:icon="#drawable/app_icon"
android:label="#string/app_name" >
<activity
android:name=".MainActivity"
android:label="Main Activity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".NextActivity" >
</activity>
</application>

button1 in activity2
code written in activity 2
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v)
{
// starting background task to update product
Intent fp=new Intent(getApplicationContext(),activity1.class);
startActivity(fp);
}
});
This might help

Simply add your NextActivity in the Manifest.XML file
<activity
android:name="com.example.sms1.NextActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
</intent-filter>
</activity>

public void onClick(View v)
{
startActivity(new Intent(getApplicationContext(), Next.class));
}
it is direct way to move second activity and there is no need for call intent

#Override
public void onClick(View v)
{
// TODO Auto-generated method stub
Intent intent = new Intent(Activity1.this,Activity2.class);
startActivity(intent);
}

1) place setContentView(R.layout.avtivity_next); to the next-activity's onCreate() method just like this (main) activity's onCreate()
2) if you have not defined the next-activity in your-apps manifest file then do this also, like:
<application
android:allowBackup="true"
android:icon="#drawable/app_icon"
android:label="#string/app_name" >
<activity
android:name=".MainActivity"
android:label="Main Activity" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".NextActivity"
android:label="Next Activity" >
</activity>
</application>
You must have to perform the 2nd step every time you create a new activity, otherwise your app will crash

When you have to go from one page to another page in android changes made in 2 files
Intent intentSignUP = new Intent(this,SignUpActivity.class);
startActivity(intentSignUP);
add activity in androidManifest file also like
<activity android:name=".SignUpActivity"></activity>

setContentView(R.layout.avtivity_next);
I think this line of code should be moved to the next activity...

Below code is working fine with Android 4.3:
Intent i = new Intent(this,MainActivity2.class);
startActivity(i);

First you have to declare the activity in Manifest. It is important. You can add this inside application like this.

It is mainly due to unregistered activity in manifest file as "NextActivity"
Firstly register NextActivity in Manifest like
<activity android:name=".NextActivity">
then use the code in the where you want
Intent intent=new Intent(MainActivity.this,NextActivity.class);
startActivity(intent);
where you have to call the NextActivity..

Register your java class on Android manifest file
After that write this code on button click
startActivity(new intent(MainActivity.this,NextActivity.class));

You can do
Intent i = new Intent(classname.this , targetclass.class);
startActivity(i);

Android Multiple Button Handle

I have created this activity with two buttons
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.content.Intent;
public class SelectOption extends Activity{
Button bu1,bu2,bu3;
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.option_main);
bu1 = (Button)findViewById(R.id.button1);
bu2 = (Button) findViewById(R.id.button2);
bu1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Intent myintent1 = new Intent(SelectOption.this, CheckBalance.class);
startActivity(myintent1);
}
});
bu2.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Intent myintent2 = new Intent(SelectOption.this, CheckAvailability.class);
startActivity(myintent2);
}
});
and there are 2 activities called CheckBalance.java and CheckAvailability.java also. but when I Run the program nothing happen on it. Does anyone have an idea what wrong with this??

Use this code in on click listener
Intent intent = new Intent();
intent.setClass(getApplicationContext(), CheckBalance.class);
startActivity(intent);
and also check weather you activities declare in manifest file and in Xml also....

This is My Manifest file (On behalf of Original question Asker(Anuradha))
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.people.oshada"
android:versionCode="1"
android:versionName="1.0" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-sdk android:minSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name" >
<activity
android:name=".TheMainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".SelectOption"></activity>
<activity android:name=".CheckBalance"></activity>
<activity android:name=".CheckAvailability"></activity>
</application>

In ANDROID MAINFEST FILE u have to add
<activity android:name=". CheckBalance"/>
<activity android:name=". CheckAvailability"/>

Cannot load new blank activity - android tutorial

I am a new android developer and encountered a problem while following the tutorial on Android's site - http://developer.android.com/training/basics/firstapp/starting-activity.html
My program loads on the emulator fine, but when you type something into the EditText and then hit the send button, a window pops up saying "App has stopped working". It seems as though my new activity isn't being created and I'm not sure as to why. I've scoured the web (and my code) to see if I could get a solution but did so to no avail. Any help would be appreciated.
The code for my first activity:
package com.example.appli;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity {
public final static String EXTRA_MESSAGE = "com.example.myapp.MESSAGE";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.testlayout);
//////Button myButton = (Button) findViewById(R.id.my_button); //Told in tutorial to put this in onCreate
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
/** Called when the user selects the Send button */
public void sendMessage(View view) {
// Do something in response to button
Intent intent = new Intent(this, DisplayMessageActivity.class);
EditText editText = (EditText) findViewById(R.id.edit_message);
String message = editText.getText().toString();
intent.putExtra(EXTRA_MESSAGE, message);
startActivity(intent);
}
}
The code for my second activity (the one being called)
package com.example.appli;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class DisplayMessageActivity extends Activity{
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//get message from intent
Intent intent = getIntent();
String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);
// Create the text view
TextView textView = new TextView(this);
textView.setTextSize(40);
textView.setText(message);
setContentView(textView);
}
}
The Manifest
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.appli"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity android:name="com.example.myapp.DisplayMessageActivity" />
<activity
android:name=".MainActivity"
android:label="#string/title_activity_main" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

In AndroidManifest File you have declared incorrect package
change
<activity android:name="com.example.myapp.DisplayMessageActivity" />
to
<activity android:name="com.example.appli.DisplayMessageActivity" />
or just
<activity android:name=".DisplayMessageActivity" />

you have declared only one Activity that's also wrong package name
already your manifest has the package name
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.appli"
so just declare like this
<activity android:name=".DisplayMessageActivity" />
and you need to add this in your manifest also
<activity android:name=".MainActivity />
remove the target SDK version that you mentioned
android:targetSdkVersion="15"

Try this
<activity android:name=".DisplayMessageActivity"/>
Instead of
<activity android:name="com.example.myapp.DisplayMessageActivity" />
in your Manifest.xml file.

You has defined the package package com.example.appli; in your activities.
Why have you defined you activity in manifest like <activity android:name="com.example.myapp.DisplayMessageActivity" />?
Replace this line with
<activity android:name=".DisplayMessageActivity" />.