我有一个带有 ViewPager 的简单片段。
我正在使用最新的支持库 v4 rev18!
如果我第一次显示它,一切正常,如果我返回并再次显示它,应用程序崩溃并出现以下异常:
java.lang.NullPointerException
at android.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:569)
at android.support.v4.app.FragmentStatePagerAdapter.restoreState(FragmentStatePagerAdapter.java:211)
at android.support.v4.view.ViewPager.onRestoreInstanceState(ViewPager.java:1281)
at android.view.View.dispatchRestoreInstanceState(View.java:12043)
at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:2688)
at android.view.ViewGroup.dispatchRestoreInstanceState(ViewGroup.java:2694)
at android.view.View.restoreHierarchyState(View.java:12021)
at android.support.v4.app.Fragment.restoreViewState(Fragment.java:425)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:949)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4800)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:798)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:565)
at dalvik.system.NativeStart.main(Native Method)
我的简单课程如下所示,实际上应该很好......
public class RoutineDayFragment extends BaseFragment
{
private RoutinesActivity mParent = null;
@InjectView(R.id.pager)
MyViewPager pager = null;
@InjectView(R.id.indicator)
PagerSlidingTabStrip indicator = null;
private FragmentStatePagerAdapter mAdapter = null;
@Override
public void onAttach(Activity activity)
{
super.onAttach(activity);
mParent = ((RoutinesActivity) getBaseActivity());
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.view_pager, container, false);
Views.inject(this, v);
mAdapter = new FragmentStatePagerAdapter(getChildFragmentManager())
{
@Override
public int getCount()
{
if (mParent.getSharedData().selectedRoutine == -1)
return 0;
return mParent.getSharedData().routines.get(mParent.getSharedData().selectedRoutine).getRWorkoutDay().size();
}
@Override
public Fragment getItem(int pos)
{
return DayFragment.newInstance(pos);
}
@Override
public CharSequence getPageTitle(int pos)
{
return Common.getString(R.string.day) + (pos + 1);
}
};
pager.setAdapter(mAdapter);
indicator.setViewPager(pager);
return v;
}
}