我需要在BrowseFragment中禁用标题，并将其添加到ArrayObjectAdapter卡片中。当我执行
setHeadersState（HEADERS_DISABLED）时，应用程序会崩溃。如果我稍后在onLoadFinished中运行setHeadersState（HEADERS_DISABLED）方法，应用程序不会崩溃，但标题栏立即可见，然后隐藏，而不是每次在适配器中显示项目时都这样做。
MainFragment.class
public class MainFragment extends BrowseFragment implements LoaderManager.LoaderCallbacks<List<Module>> {
private static final int MODULES_LOADER_ID = 100;
private ArrayObjectAdapter mRowsAdapter;
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setupUIElements();
setupRowAdapter();
setupListeners();
getLoaderManager().initLoader(MODULES_LOADER_ID, null, this);
}
private void setupUIElements() {
setTitle(getActivity().getString(R.string.app_name));
setBadgeDrawable(getResources().getDrawable(R.drawable.title, getActivity().getTheme()));
setHeadersTransitionOnBackEnabled(false);
setBrandColor(getActivity().getResources().getColor(R.color.fastlane_background));
setHeadersState(HEADERS_DISABLED);
}
private void setupRowAdapter() {
mRowsAdapter = new ArrayObjectAdapter(new ListRowPresenter());
setAdapter(mRowsAdapter);
}
private void setupListeners() {
setOnItemViewSelectedListener(new ItemViewSelectedListener());
setOnItemViewClickedListener(new ItemViewClickedListener());
}
private void loadModules(List<Module> modules) {
ArrayObjectAdapter listRowAdapter = new ArrayObjectAdapter(new ModulesCardPresenter());
for (Module module : modules) {
listRowAdapter.add(module);
}
HeaderItem header = new HeaderItem(0, "Меню");
mRowsAdapter.add(new ListRow(header, listRowAdapter));
}
@Override
public Loader<List<Module>> onCreateLoader(int id, Bundle args) {
switch (id) {
case MODULES_LOADER_ID:
return new ModulesLoader(getActivity());
default:
return null;
}
}
@Override
public void onLoadFinished(Loader<List<Module>> loader, List<Module> data) {
switch (loader.getId()) {
case MODULES_LOADER_ID:
loadModules(data);
break;
}
}
@Override
public void onLoaderReset(Loader<List<Module>> loader) {
}
static class ModulesLoader extends SimpleAsyncTaskLoader<List<Module>> {
public ModulesLoader(Context context) {
super(context);
}
@Override
public List<Module> loadInBackground() {
Call<Modules> mCall = ServiceHolder.getService()
.getModules(Constants.GET_MODULES_REQUEST);
try {
return mCall.execute().body().getModules();
} catch (Exception e) {
e.printStackTrace();
return Collections.EMPTY_LIST;
}
}
}
private final class ItemViewSelectedListener implements OnItemViewSelectedListener {
@Override
public void onItemSelected(Presenter.ViewHolder itemViewHolder, Object item,
RowPresenter.ViewHolder rowViewHolder, Row row) {
}
}
private final class ItemViewClickedListener implements OnItemViewClickedListener {
@Override
public void onItemClicked(Presenter.ViewHolder itemViewHolder, Object item,
RowPresenter.ViewHolder rowViewHolder, Row row) {
}
}
日志：
08-18 16:06:08.331 29647-29647/ E/AndroidRuntime: FATAL EXCEPTION: main
Process: , PID: 29647
**java.lang.RuntimeException: Unable to start activity ComponentInfo{.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Fragment.getView()' on a null object reference**
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
**Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.app.Fragment.getView()' on a null object reference**
at android.support.v17.leanback.app.BrowseFragment.onStart(BrowseFragment.java:1511)
at android.app.Fragment.performStart(Fragment.java:2244)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1002)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1130)
at android.app.FragmentManagerImpl.dispatchStart(FragmentManager.java:1958)
at android.app.FragmentController.dispatchStart(FragmentController.java:163)
at android.app.Activity.performStart(Activity.java:6274)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) </code>
MainFragment添加到视图中的？你是通过XML添加还是使用片段管理器？ - Kyle VennMainFragment fragment = new MainFragment(); getFragmentManager() .beginTransaction() .replace(R.id.fragment_container, fragment) .commit();- Andrei Anhurets