我正在使用此实现 http://developer.android.com/training/implementing-navigation/lateral.html#horizontal -paging 创建一个类似视图的画廊,其中包含视图寻呼机和片段。
在我的代码中,我将从 web 服务器的 viewpager 中为特定的登录用户获取 NUM_PAGES(整数)。
我在做什么:
当用户登录到应用程序时,我的页面会填充信息,该应用程序会执行许多检查以填充一个页面,因此我在调用 onCreate() 时创建了所有视图,并在每次片段需要它们时重用它们。
当我在 viewpager 中启动具有多个页面的应用程序时,在第 1 页到第 5 页之间导航时,该应用程序运行良好,当我尝试重新访问上一页时,该应用程序因“java.lang.IllegalStateException”而崩溃。
我是 Fragments 和 viewpager 的新手,请帮我解决这个问题。
提前致谢。
基兰
FATAL EXCEPTION: main
java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
at android.view.ViewGroup.addViewInner(ViewGroup.java:3435)
at android.view.ViewGroup.addView(ViewGroup.java:3306)
at android.view.ViewGroup.addView(ViewGroup.java:3251)
at android.view.ViewGroup.addView(ViewGroup.java:3227)
at android.support.v4.app.NoSaveStateFrameLayout.wrap(NoSaveStateFrameLayout.java:40)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:931)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
我的代码:
protected void onCreate(Bundle savedInstance){
//my code here
//prepare views to be used with viewpager
setupViews();
//setup viewpager stuff
mAdapter = new ViewsAdapter(getSupportFragmentManager());
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
setContentView(R.layout.activity_main);
//other initializations here
}
public static class ViewsAdapter extends FragmentStatePagerAdapter{
public ViewsAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
// TODO Auto-generated constructor stub
}
@Override
public Fragment getItem(int position) {
// TODO Auto-generated method stub
Fragment fragment = new VehicleFragment();
Bundle args = new Bundle();
args.putInt(VehicleFragment.VEHICLE_INDEX, position);
fragment.setArguments(args);
return fragment;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return NUM_PAGES;// this value will be fetched at runtime from a server.
}
}
public class VehicleFragment extends Fragment {
public static final String VEHICLE_INDEX = "VEHICLE_INDEX";
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
Bundle args = getArguments();
int position = args.getInt(VEHICLE_INDEX);
Log.i("VehicleHome", "retrieving position : "+position+" in viewsList, where viewsList size = "+viewsList.size());
return viewsList.get(position);
}
}
private void setupViews() {
//prepare Views here, the views are created at runtime and added to viewsList (ArrayList)
//for reuse with fragments. So that each time a new instance of fragment is created we won't endup
//inflating layout file and initializing the view again and again..
//views logic
viewsList.add(view);
}