Develop Reference

Cant start new activity. It keeps crashing

When pressing the button, new activity should open but app instantly crashes. I have searched for answer and making a few adjustments to my code and only thing i dont know how to do is Manifest, can u help me with that?
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="Starting.Programm"
android:versionCode="1"
android:versionName="1.0">
<application android:label="#string/app_name"
android:icon="#drawable/ic_launcher">
<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="InformationActivity"
android:label="#string/app_name"
>
</activity>
</application>
MainActivity:
package Starting.Programm;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
public class MainActivity extends InformationActivity
{
/** Called when the activity is first created. */
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
public void startJourney(View view) {
Intent intent = new Intent(this, InformationActivity.class);
startActivity(intent);
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
tools:context=".MainActivity"
>
<Button android:id="#+id/button_StartApp"
android:layout_width="100dp"
android:layout_height="60dp"
android:text="#string/button_StartApp"
android:layout_gravity="center"
android:layout_marginTop="70dp"
android:layout_marginLeft="115dp"
android:onClick="startJourney"
/>
</LinearLayout>
And next activity which should be opening
package Starting.Programm;
import android.app.Activity;
import android.os.Bundle;
class InformationActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.information);
}
}

<activity> android:name=".InformationActivity" </activity>
Remove android:label="#string/app_name" too. I don't think it is needed.

Add dot to end of pacakager name
package="Starting.Programm."

java.lang.IllegalStateException: Could not execute method of the activity - starting new Activity

I am trying to start a New Activity using Intent but I keep getting java.lang.IllegalStateException: Could not execute method of the activity
What am I doing wrong?
Main Activity
package com.example.wrw;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void clicked(View v)
{
Intent intent = new Intent(this, newact.class);
startActivity(intent);
}
}
newact.java
package com.example.wrw;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
public class newact extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.newlayout);
}
}
act_main.xml
<LinearLayout 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:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start Act"
android:onClick="clicked"
/>
</LinearLayout>
newlayout.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
</LinearLayout>
Manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.wrw"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<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>
</application>
</manifest>

In android app, all Activity must be configured in the Manifest.xml file firstly, so you should add newact Activity to your manifest
<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="com.example.wrw.newact"></activity>

Add this to your manifest file
<activity
android:name=".newact"
android:label="#string/title_activity_login">

Replace this to your MainActivity, this may resolve your problem.
Intent intent = new Intent(MainActivity.this, newact.class);
startActivity(intent);
After this, do not forget to add this in your android menifest file,
<activity
android:name=".newact"
android:label="#string/app_name">
</activity>

try this
Intent intent = new Intent(MainActivity.this, newact.class)
and also register newact in manifest file like this
<activity
android:name=".newact"
android:label="#string/app_name">
</activity>

unfortunately API demo has stopped while running

I have developed an app for page navigation . when a button is clicked the page should navigate to the second page. when i run the project and opened my app its showing unfortunately API demo has stopped. I have posted the entire code of my app . PLS HELP ME OUT...
//MAIN ACTIVITY
<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" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/textView1"
android:layout_marginLeft="73dp"
android:layout_marginTop="14dp"
android:text="Click" />
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/button1"
android:layout_alignParentTop="true"
android:layout_marginLeft="14dp"
android:layout_marginTop="34dp"
android:text="Main Activity" />
</RelativeLayout>
//SECONDSCREEN ACTIVITY
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sceond Screen Activity"
tools:context=".SecondScreenActivity"/>
</LinearLayout>
//JAVA CODE FOR MAIN ACTIVITY
package com.example.navigate;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addButtonOnClickEventListener();
}
public void addButtonOnClickEventListener()
{
Button button = (Button)findViewById(R.id.button1);
final Context context = this;
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(context,SecondScreenActivity.class);
startActivity(intent);
}
});
}
#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;
}
}
// JAVA CODE FOR SECOND SCREEN ACTIVITY
package com.example.navigate;
import android.app.Activity;
public class SecondScreenActivity extends Activity {
}
// MANIFEST FILE
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.navigate"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.navigate.SecondScreenActivity"
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>

First problem MainActivity is your launcher page here but you define the secondactivity as luncher in manifest.change it first.
Add an oncreate() to secondactivity otherwise there is nothing to show when the button click.
Third change your MainActivity Context to activity which is MainActivity.this not local
Other things are fine , and hope you understand your small problems..
Change your manifest to something like this:
// MANIFEST FILE
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.navigate.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 = ".SecondScreenActivity" />
</application>
And in your SecondScreenActivity add an oncreate method with the contet view like:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.secondactivity_layout);
}
And also in your mainactivity change the context to MainActivity.this . Here you define the context inside onclicklistener which links to your local method not the class.

admob does not show up in android

I'm a beginner,I'm trying to set an admob add in my app.But I have some errors witch I can't manage.
XmlFile
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<com.google.ads.AdView android:id="#+id/main"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
ads:adUnitId="MY_AD_UNIT_ID"
ads:adSize="BANNER"
ads:testDevices="TEST_EMULATOR, TEST_DEVICE_ID"
ads:loadAdOnCreate="true"/>
</RelativeLayout>
Manifest File.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.admob"
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.admob.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="com.google.ads.AdActivity"
android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|scre enSize|smallestScreenSize" />
</application>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
</manifest>
Java Code:
package com.example.admob;
import com.google.ads.AdRequest;
import com.google.ads.AdSize;
import com.google.ads.AdView;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
public class MainActivity extends Activity
{
private static final String MY_AD_UNIT_ID = null;
private AdView adView;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
adView = new AdView(this, AdSize.BANNER, MY_AD_UNIT_ID);
RelativeLayout main = (RelativeLayout)findViewById(R.id.main);
main.addView(adView);
adView.loadAd(new AdRequest());
AdRequest adRequest = new AdRequest();
adRequest.addTestDevice(AdRequest.TEST_EMULATOR);
adRequest.addTestDevice("TEST_DEVICE_ID");
}
#Override
public void onDestroy() {
adView.destroy();
super.onDestroy();
}
}
when Activity start this type error occur onFailedToReceivedAd(InvalidAdRequest).
I don't know what is the problem.

You are not loading the AdRequest which has the test devices registered. Change your code to:
//....
main.addView(adView);
AdRequest adRequest = new AdRequest();
adRequest.addTestDevice(AdRequest.TEST_EMULATOR);
adRequest.addTestDevice("TEST_DEVICE_ID");
adView.loadAd(adRequest);

In your relativelayout that contains the adview, are you appending the content layout after the adview. If so, what are the android:layout_width and android:layout_height values. If you are using fill_parent/match_parent for both, then your adview will never show.
The trick is to change the relativelayout to the linearlayout. Then for the content layout within this linearlayout, set its android:layout_width="fill_parent" and android:layout_height="0dp". Add a new attribute android:layout_weight="1" for the content layout. What these does is to ask the content layout to accomodate the remaining space of linearlayout after the adview has occupied its place. Hope this helps.

Android application crases when switching activity

I have a problem with an Android aplication. When I try to swich from main activity (PretvornikValut) to another one (Pretvornik) via buttun I get the "Unfortunately aplication stopped working" error. Can anyone help?
PretvornikValut.java
package pretvornik.valut;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
public class PretvornikValut extends Activity implements OnClickListener
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
View gumbPretvori = findViewById(R.id.gumb_pretvornik);
gumbPretvori.setOnClickListener(this);
View gumbTecaji = findViewById(R.id.gumb_tecaji);
gumbTecaji.setOnClickListener(this);
}
public void sendMessage(View view) {
Intent intent = new Intent(this, Pretvornik.class);
startActivity(intent);
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.gumb_pretvornik:
Intent i = new Intent(this, Pretvornik.class);
//i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(i);
break;
case R.id.gumb_tecaji:
Intent tecaj = new Intent(this, Tecaji.class);
tecaj.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(tecaj);
break;
}
}
}
Pretvornik java
package pretvornik.valut;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
/**
*
* #author FAKS
*/
public class Pretvornik extends Activity {
/**
* Called when the activity is first created.
*/
#Override
public 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.pretvornik);
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#99CCCC"
>
<Button
android:id="#+id/gumb_pretvornik"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_alignParentLeft="true"
android:layout_alignParentBottom="true"
android:text="Pretvornik"
/>
<Button
android:id="#+id/gumb_tecaji"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_toRightOf="#+id/OK"
android:layout_alignParentBottom="true"
android:text="Izpis tecajev"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Izberi zeljeno opcijo"
/>
</LinearLayout>
pretvornik.xml
<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#99CCCC"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="glavni program"
/>
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="pretvornik.valut"
android:versionCode="1"
android:versionName="1.0">
<application android:label="#string/app_name" android:icon="#drawable/ic_launcher">
<activity android:name="PretvornikValut"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<activity
android:name="Pretvornik"
android:label="#string/Pretvornik_valut" >
<meta-data
android:name="PretvornikValut"
/>
</activity>
<activity
android:name="Tecaji"
android:label="#string/Izpis_tecajev" >
<meta-data
android:name="PretvornikValut"
/>
</activity>
</activity>
</application>
</manifest>

Change your manifest xml,
add action for your activities
action android:name="android.intent.action.ACTIVITY"
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="pretvornik.valut"
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="PretvornikValut"
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="Pretvornik"
android:label="#string/hello_world" >
<action android:name="android.intent.action.ACTIVITY" />
</activity>
<activity
android:name="Tecaji"
android:label="#string/hello_world" >
<action android:name="android.intent.action.ACTIVITY" />
</activity>
</application>
</manifest>