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我将问题缩小为fragmentManager保留旧片段实例的问题，并且viewpager与FragmentManager不同步。请参阅此问题... http://code.google.com/p/android/issues/detail?id=19211#makechanges。我仍然不知道如何解决这个问题。有什么建议...
我已经尝试调试了很长时间，任何帮助将不胜感激。我正在使用FragmentPagerAdapter，它接受像这样的片段列表：
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, Fragment1.class.getName()));
...
new PagerAdapter(getSupportFragmentManager(), fragments);实施是标准的。我正在为片段使用ActionBarSherlock和v4可计算性库。
我的问题是，离开应用程序并打开其他几个应用程序并返回后，这些片段会丢失对FragmentActivity的引用（即getActivity() == null）。我不知道为什么会这样。我试图手动设置，setRetainInstance(true);但这无济于事。我认为这是在我的FragmentActivity被销毁时发生的，但是如果在收到日志消息之前打开应用程序，这种情况仍然会发生。有什么想法吗？
@Override
protected void onDestroy(){
Log.w(TAG, "DESTROYDESTROYDESTROYDESTROYDESTROYDESTROYDESTROY");
super.onDestroy();
}适配器：
public class PagerAdapter extends FragmentPagerAdapter {
private List<Fragment> fragments;
public PagerAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
}
@Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}
@Override
public int getCount() {
return this.fragments.size();
}
}我的片段之一被剥夺了，但是我很高兴地证明了一切都被剥夺了，但仍然无法正常工作...
public class MyFragment extends Fragment implements MyFragmentInterface, OnScrollListener {
...
@Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
handler = new Handler();
setHasOptionsMenu(true);
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
Log.w(TAG,"ATTACHATTACHATTACHATTACHATTACH");
context = activity;
if(context== null){
Log.e("IS NULL", "NULLNULLNULLNULLNULLNULLNULLNULLNULLNULLNULL");
}else{
Log.d("IS NOT NULL", "NOTNOTNOTNOTNOTNOTNOTNOT");
}
}
@Override
public void onActivityCreated(Bundle savedState) {
super.onActivityCreated(savedState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.my_fragment,container, false);
return v;
}
@Override
public void onResume(){
super.onResume();
}
private void callService(){
// do not call another service is already running
if(startLoad || !canSet) return;
// set flag
startLoad = true;
canSet = false;
// show the bottom spinner
addFooter();
Intent intent = new Intent(context, MyService.class);
intent.putExtra(MyService.STATUS_RECEIVER, resultReceiver);
context.startService(intent);
}
private ResultReceiver resultReceiver = new ResultReceiver(null) {
@Override
protected void onReceiveResult(int resultCode, final Bundle resultData) {
boolean isSet = false;
if(resultData!=null)
if(resultData.containsKey(MyService.STATUS_FINISHED_GET)){
if(resultData.getBoolean(MyService.STATUS_FINISHED_GET)){
removeFooter();
startLoad = false;
isSet = true;
}
}
switch(resultCode){
case MyService.STATUS_FINISHED:
stopSpinning();
break;
case SyncService.STATUS_RUNNING:
break;
case SyncService.STATUS_ERROR:
break;
}
}
};
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
menu.clear();
inflater.inflate(R.menu.activity, menu);
}
@Override
public void onPause(){
super.onPause();
}
public void onScroll(AbsListView arg0, int firstVisible, int visibleCount, int totalCount) {
boolean loadMore = /* maybe add a padding */
firstVisible + visibleCount >= totalCount;
boolean away = firstVisible+ visibleCount <= totalCount - visibleCount;
if(away){
// startLoad can now be set again
canSet = true;
}
if(loadMore)
}
public void onScrollStateChanged(AbsListView arg0, int state) {
switch(state){
case OnScrollListener.SCROLL_STATE_FLING:
adapter.setLoad(false);
lastState = OnScrollListener.SCROLL_STATE_FLING;
break;
case OnScrollListener.SCROLL_STATE_IDLE:
adapter.setLoad(true);
if(lastState == SCROLL_STATE_FLING){
// load the images on screen
}
lastState = OnScrollListener.SCROLL_STATE_IDLE;
break;
case OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:
adapter.setLoad(true);
if(lastState == SCROLL_STATE_FLING){
// load the images on screen
}
lastState = OnScrollListener.SCROLL_STATE_TOUCH_SCROLL;
break;
}
}
@Override
public void onDetach(){
super.onDetach();
if(this.adapter!=null)
this.adapter.clearContext();
Log.w(TAG, "DETACHEDDETACHEDDETACHEDDETACHEDDETACHEDDETACHED");
}
public void update(final int id, String name) {
if(name!=null){
getActivity().getSupportActionBar().setTitle(name);
}
}}
当用户与其他片段进行交互并且getActivity返回null时，将调用update方法。这是另一个片段正在调用的方法...
((MyFragment) pagerAdapter.getItem(1)).update(id, name);我相信，当应用程序被销毁后又被创建，而不是仅仅将应用程序启动到默认片段，应用程序就会启动，然后viewpager导航到最后一个已知页面。这似乎很奇怪，应用程序不应该加载到默认片段吗？
27
Android的Fragment很烂！
—
Hamidreza Sadegh
上帝，我爱您的日志消息：D
—
oli.G，2015年