I'm trying to implement toolbar tabs, and have each tab inflate a different fragment, however I am stuck with the error:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.danielkim.soundrecorder/com.danielkim.soundrecorder.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference
Here is my Adapter in MainActivity.java:
public class MyAdapter extends FragmentPagerAdapter {
private String[] titles = { "Record", "Saved Recordings" };
public MyAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch(position){
case 0:{
return RecordFragment.newInstance(position);
}
case 1:{
return FileViewerFragment.newInstance(position);
}
}
return null;
}
@Override
public int getCount() {
return titles.length;
}
@Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
}
and RecordFragment.java:
public static RecordFragment newInstance(int position) {
RecordFragment f = new RecordFragment();
Bundle b = new Bundle();
b.putInt(ARG_POSITION, position);
f.setArguments(b);
return f;
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
position = getArguments().getInt(ARG_POSITION);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View recordView = inflater.inflate(R.layout.fragment_record, container, false);
mChronometer = (Chronometer) recordView.findViewById(R.id.chronometer);
mRecordButton = (FloatingActionButton) recordView.findViewById(R.id.btnRecord);
mRecordButton.setColorNormal(getResources().getColor(R.color.accent));
mRecordButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onRecord(mStartRecording);
mStartRecording = !mStartRecording;
}
});
mPauseButton = (ImageButton) recordView.findViewById(R.id.btnPause);
mPauseButton.setVisibility(View.GONE); //hide pause button before recording starts
return recordView;
}
any help would be appreciated, thanks!
edit:
Here is the full stack trace. I changed the Adapter to use return RecordFragment.newInstance(position) instead, but still seeing the same errors.
12-25 16:16:42.845 2889-2889/com.danielkim.soundrecorder E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.danielkim.soundrecorder, PID: 2889
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.danielkim.soundrecorder/com.danielkim.soundrecorder.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
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)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference
at com.danielkim.soundrecorder.fragments.RecordFragment.onCreate(RecordFragment.java:76)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1763)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:913)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1220)
at android.app.Activity.performStart(Activity.java:5949)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2261)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
at android.app.ActivityThread.access$800(ActivityThread.java:144)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
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)
getArguments() is returning null (hence, the NPE at getArguments().getInt(ARG_POSITION)) because you haven't called setArguments() after creating the Fragment.
The usual pattern is to have a factory method in the Fragment class that preloads the arguments. In this case, it should be something more or less like:
public static RecordFragment newInstance(int position) {
RecordFragment f = new RecordFragment();
Bundle args = new Bundle();
args.putInt(ARG_POSITION, position);
f.setArguments(args);
return f;
}
Then create the Fragment using this method, instead of calling the constructor directly.
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