我正在开发一个包含ViewPager
和Fragment
的Android应用程序,结构如下:
MainActivity
(MainActivityFragment
(screenSlideViewPager
(Fragment
s))),这意味着:
Activity
包含 Fragment
包含 ViewPager
包含 Fragment
s
现在我的问题是,当旋转设备或更改屏幕方向时,ViewPager中的所有Fragment都会消失。
有什么解决方法吗?
编辑1
MainActivity.java:
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getSupportFragmentManager().findFragmentByTag(TAG) == null) {
final FragmentTransaction ft = getSupportFragmentManager()
.beginTransaction();
ft.add(android.R.id.content, new MainActivityFragment(), TAG);
ft.commit();
}
}
MainActivityFragment.java:
public class MainActivityFragment extends Fragment {
private ViewPager mPager = null;
private PagerAdapter mPageAdapter = null;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View reVal = inflater.inflate(R.layout.activity_main, container, false);
mPager = (ViewPager) reVal.findViewById(R.id.pagerMainContent);
mPageAdapter = new ScreenSlidePagerAdapter(getActivity().getFragmentManager());
mPager.setAdapter(mPageAdapter);
return reVal;
}
private MainGridViewFragment mainGridFragment;
private AlphabetGridViewFragment alphabetGridFragment;
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public android.app.Fragment getItem(int position) {
switch (position) {
case 1:
mainGridFragment = new MainGridViewFragment();
return mainGridFragment;
case 0:
alphabetGridFragment = new AlphabetGridViewFragment();
return alphabetGridFragment;
default:
return null;
}
}
@Override
public int getCount() {
return 2;
}
}
}
EDIT 2
显然,MainActivity
和MainActivityFragment
已经加载,证明是由于出现了ActionBar
。请注意,ViewPager
也已经加载,因为您仍然可以在页面之间进行导航(蓝色指示灯表示分页器已到达最后一页),但是您无法看到其内容。