Thursday, February 10, 2011

[android-developers] Button click Navigation not working ( application gets crashes)

This is manifest.xml file:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="button.pack"
android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/
app_name">
<activity android:name=".Activity1"
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=".Activity2"></activity>
</application>
<uses-sdk android:minSdkVersion="8" />
</manifest>

.....

Java file: Activity1.Java


package button.pack;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class Activity1 extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.main);

Button next = (Button) findViewById(R.id.Button01);
next.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent myIntent = new Intent(view.getContext(),
Activity2.class);
startActivityForResult(myIntent, 0);
}

});
}
}

Java file: Activity2.Java

package button.pack;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class Activity2 extends Activity {

/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);

Button next = (Button) findViewById(R.id.Button02);
next.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent();
setResult(RESULT_OK, intent);
finish();
}

});

}
}

...................................


Xml Files...
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="#ffffff" >

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#000000"
android:text="This is Activity 2" />

<Button
android:text="Previous"
android:id="@+id/Button02"
android:layout_width="250px"
android:textSize="18px"
android:layout_height="55px">
</Button>
</LinearLayout>
............................................
main2.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="#ffffff">

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textColor="#000000"
android:text="This is Activity 1" />

<Button android:layout_width="250px"
android:textSize="18px"
android:layout_height="55px"
android:id="@+id/Button01"
android:text="Next">
</Button>

</LinearLayout>
..............................................

This my Logcat:


02-10 13:33:53.962: ERROR/AndroidRuntime(1756): FATAL EXCEPTION: main
02-10 13:33:53.962: ERROR/AndroidRuntime(1756):
java.lang.RuntimeException: Unable to start activity
ComponentInfo{button.pack/button.pack.Activity1}:
java.lang.NullPointerException
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
1622)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:
1638)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread.access$1500(ActivityThread.java:117)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:928)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.os.Handler.dispatchMessage(Handler.java:99)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.os.Looper.loop(Looper.java:123)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread.main(ActivityThread.java:3647)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
java.lang.reflect.Method.invokeNative(Native Method)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
java.lang.reflect.Method.invoke(Method.java:507)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
com.android.internal.os.ZygoteInit
$MethodAndArgsCaller.run(ZygoteInit.java:839)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
dalvik.system.NativeStart.main(Native Method)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): Caused by:
java.lang.NullPointerException
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
button.pack.Activity1.onCreate(Activity1.java:18)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:
1047)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:
1586)
02-10 13:33:53.962: ERROR/AndroidRuntime(1756): ... 11 more
..........................................................


Please Any one find solution for the above scenario.....


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