I'm getting the following exception from my android app:
FATAL EXCEPTION: main
java.lang.IllegalStateException: Fragment null must be a public static class to be properly recreated from instance state.
at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:435)
at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:420)
at android.support.v4.app.FragmentStatePagerAdapter.instantiateItem(FragmentStatePagerAdapter.java:123)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1006)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1154)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1088)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:389)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:15525)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2438)
at android.view.View.measure(View.java:15525)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
at android.view.Choreographer.doCallbacks(Choreographer.java:562)
at android.view.Choreographer.doFrame(Choreographer.java:532)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5227)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
at dalvik.system.NativeStart.main(Native Method)
Unfortunately, the exception doesn't have a reference to my code. It appears as soon as I start an activity with fragments in it. I think the following is the relevant part of my code:
public class MonthViewActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_month);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
viewPager.setAdapter(new FragmentStatePagerAdapter(getSupportFragmentManager()) {
@Override
public Fragment getItem(final int position) {
return new Fragment() {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.month_view, container, false);
return rootView;
}
};
}
@Override
public int getCount() {
return 12;
}
});
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
}
@Override
public void onPageSelected(int position) {
Month month = Year.getCurrent().getMonth(position);
TextView month_name = (TextView) findViewById(R.id.month_name);
month_name.setText(month.getName());
}
@Override
public void onPageScrollStateChanged(int state) {
}
});
viewPager.setCurrentItem(getIntent().getExtras().getInt("month"));
if (getIntent().getExtras().getInt("month") == 0) {
// The OnPageChangeListener doesn't do it for the first one
Month month = Year.getCurrent().getMonth(0);
TextView month_name = (TextView) findViewById(R.id.month_name);
month_name.setText(month.getName());
}
}
}
This exception wasn't thrown from my app when I was using Android Studio 1.5.1. It appeared just now after I upgraded to Android Studio 2.1.3.
Somebody else seems to have a similar problem: Fragment must be a public static class to be properly recreated from instance state However, I couldn't find a solution there.
