AM getting force close on emulator while rotating from portrait to Landscape? I already tried adding in manifest android:configChanges="keyboard|keyboardHidden"
02-05 17:29:52.321: E/AndroidRuntime(1192): FATAL EXCEPTION: main
02-05 17:29:52.321: E/AndroidRuntime(1192): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.kidzapp.sample/com.kidzapp.sample.alphabets}: java.lang.NullPointerException
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.os.Handler.dispatchMessage(Handler.java:99)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.os.Looper.loop(Looper.java:123)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-05 17:29:52.321: E/AndroidRuntime(1192): at java.lang.reflect.Method.invokeNative(Native Method)
02-05 17:29:52.321: E/AndroidRuntime(1192): at java.lang.reflect.Method.invoke(Method.java:521)
02-05 17:29:52.321: E/AndroidRuntime(1192): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
02-05 17:29:52.321: E/AndroidRuntime(1192): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
02-05 17:29:52.321: E/AndroidRuntime(1192): at dalvik.system.NativeStart.main(Native Method)
02-05 17:29:52.321: E/AndroidRuntime(1192): Caused by: java.lang.NullPointerException
02-05 17:29:52.321: E/AndroidRuntime(1192): at com.kidzapp.sample.alphabets.onCreate(alphabets.java:68)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
02-05 17:29:52.321: E/AndroidRuntime(1192): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
This is my code:
public class alphabets extends Activity implements OnClickListener{
ImageButton home;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.lower);
home=(ImageButton)findViewById(R.id.home);
home.setOnClickListener(this);
}
public void onClick(View image) {
// TODO Auto-generated method stub
switch (image.getId()) {
case R.id.home:
Intent i=new Intent(this, MainActivity.class);
startActivity(i);
finish();
break;
}
}
@Override
protected void onStop() {
// TODO Auto-generated method stub
mp.stop();
super.onStop();
}
It seems that your ImageView home
view is NULL that why when you try to set your clickListener it crashes:
home.setOnClickListener(this);
If it only occurs when you are in landscape mode, I think it's because you are using a specific layout for landscape orientation (directory res/layout-land
) and this layout does not have an ImageView
with the R.id.home
identifier.
Edit:
One more thing, you do not need to add android:configChanges="keyboard|keyboardHidden"
to your manifest. It's not the cause of your problem and it's discouraged for Android development expect for some really specific case.
In the official documentation :
This technique should be considered a last resort when you must avoid restarts due to a configuration change and is not recommended for most applications.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.