尝试在空对象引用上调用虚拟方法 'android.widget.Filter com.app.app.adapter.TextTypingCustomAdapter.getFilter()'

Question

我为搜索视图添加了一个过滤器，以显示与查询匹配的recyclerview项。搜索似乎有效，但如果recyclerview中没有物品，应用程序就会崩溃，所以有人能帮我吗？

我的碎片：

public class TextTypingTabFragment extends Fragment implements TabLayoutFragmentPagerAdapter.ITabLayoutIconFragmentPagerAdapter {
private static final String TAG = TextTypingTabFragment.class.getSimpleName();
private final TextTypingLoaderCallbacks mLoaderCallbacks = new TextTypingLoaderCallbacks();
private TextTypingCustomAdapter mTextTypingCustomAdapter;
private View mView;
private ProgressBar mProgressBar;
private ScrollView mScrollView;
private RecyclerView mRecyclerView;
public TextTypingTabFragment() {
// Required empty public constructor
}
// ----
private Context getContextNonNull() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
return Objects.requireNonNull(getContext());
} else {
return getContext();
}
}
// ----
private int mItemCount = -1;
private int mFirstVisibleItemPosition = -1, mFirstCompletelyVisibleItemPosition = -1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LogUtil.d(TAG, "Fragment create");
Bundle bundle = new Bundle();
bundle.putString(AppEnvr.EXTRA_PACKAGE_NAME_KEY, MainActivity.sSelectedPackageName);
getLoaderManager().initLoader(1, bundle, mLoaderCallbacks); // Init with 1
setHasOptionsMenu(true);
// ----
LocalBroadcastManager.getInstance(getContextNonNull()).registerReceiver(mSelectedPackageNameChangedCustomReceiver, new IntentFilter(AppEnvr.ACTION_SELECTED_PACKAGE_NAME_CHANGED));
}
@Override
public void onResume() {
super.onResume();
LogUtil.d(TAG, "Fragment resume");
Bundle bundle = new Bundle();
bundle.putString(AppEnvr.EXTRA_PACKAGE_NAME_KEY, MainActivity.sSelectedPackageName);
getLoaderManager().restartLoader(1, bundle, mLoaderCallbacks); // Restart with 1
}
@Override
public void onPause() {
super.onPause();
LogUtil.d(TAG, "Fragment pause");
if (mTextTypingCustomAdapter != null) {
mItemCount = mTextTypingCustomAdapter.getItemCount();
}
if (mRecyclerView != null) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) mRecyclerView.getLayoutManager();
if (linearLayoutManager != null) {
mFirstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
mFirstCompletelyVisibleItemPosition = linearLayoutManager.findFirstCompletelyVisibleItemPosition();
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
LogUtil.d(TAG, "Fragment destroy");
LocalBroadcastManager.getInstance(getContextNonNull()).unregisterReceiver(mSelectedPackageNameChangedCustomReceiver);
}
// ----
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_text_typing_tab, container, false);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
mView = view;
mProgressBar = view.findViewById(R.id.fragment_text_typing_tab_progress_bar);
mScrollView = view.findViewById(R.id.fragment_text_typing_tab_scroll_view);
mRecyclerView = view.findViewById(R.id.fragment_text_typing_tab_recycler_view);
}
// ----
@Override
public Fragment getItem() {
return this;
}
@Override
public CharSequence getPageTitle() {
return "History";
}
@Override
public int getIcon() {
return R.drawable.ic_typesave;
}
@Override
public void onCreateOptionsMenu(@NonNull Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.typed_text_fragment_menu, menu);
final SearchView searchView = new SearchView(getActivity());
searchView.setQuery(null, true);
searchView.setQueryHint("Search");
EditText searchEditText = searchView.findViewById(androidx.appcompat.R.id.search_src_text);
searchEditText.setTextColor(getResources().getColor(R.color.white));
searchEditText.setHintTextColor(getResources().getColor(R.color.tabTextColor));
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String s) {
Filter filter = mTextTypingCustomAdapter.getFilter();
if (filter != null) {
filter.filter(s);
return true;
}
return false;
}
@Override
public boolean onQueryTextChange(String s) {
Filter filter = mTextTypingCustomAdapter.getFilter();
if (filter != null) {
filter.filter(s);
return true;
}
return false;
}
});
menu.findItem(R.id.action_search).setActionView(searchView);
}
// ----
private final BroadcastReceiver mSelectedPackageNameChangedCustomReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
LogUtil.d(TAG, "Receiver receive");
// ----
if (context == null || intent == null) {
if (context == null) {
LogUtil.w(TAG, "Receiver receive: Context lack");
}
if (intent == null) {
LogUtil.w(TAG, "Receiver receive: Intent lack");
}
return;
}
// ----
String intentAction = null;
try {
intentAction = intent.getAction();
} catch (Exception e) {
LogUtil.e(TAG, e.getMessage());
LogUtil.e(TAG, e.toString());
e.printStackTrace();
}
if (intentAction == null || !intentAction.equals(AppEnvr.ACTION_SELECTED_PACKAGE_NAME_CHANGED)) {
if (intentAction == null) {
LogUtil.w(TAG, "Receiver receive: Intent action lack");
} else if (!intentAction.equals(AppEnvr.ACTION_SELECTED_PACKAGE_NAME_CHANGED)) {
LogUtil.w(TAG, "Receiver receive: Intent action mismatch");
}
return;
}
// ----
LogUtil.d(TAG, "Receiver receive: OK");
// ----
Bundle extras = null;
try {
extras = intent.getExtras();
} catch (Exception e) {
LogUtil.e(TAG, e.getMessage());
LogUtil.e(TAG, e.toString());
e.printStackTrace();
}
if (extras != null) {
if (extras.containsKey(AppEnvr.EXTRA_PACKAGE_NAME_KEY)) {
String packageName = extras.getString(AppEnvr.EXTRA_PACKAGE_NAME_KEY, null);
// ----
Bundle bundle = new Bundle();
bundle.putString(AppEnvr.EXTRA_PACKAGE_NAME_KEY, packageName);
getLoaderManager().restartLoader(1, bundle, mLoaderCallbacks); // Restart with 1
}
}
}
};
// ----
private final class TextTypingLoaderCallbacks implements LoaderManager.LoaderCallbacks<ArrayList<TextTypingObject>> {
private String mPackageName = null;
@NonNull
@Override
public Loader<ArrayList<TextTypingObject>> onCreateLoader(int i, @Nullable Bundle bundle) {
if (mScrollView != null) {
mScrollView.setVisibility(View.GONE);
}
if (mRecyclerView != null) {
mRecyclerView.setVisibility(View.GONE);
}
if (mProgressBar != null) {
mProgressBar.setVisibility(View.VISIBLE);
}
// ----
if (bundle != null) {
mPackageName = bundle.getString(AppEnvr.EXTRA_PACKAGE_NAME_KEY, null);
}
// ----
return new TextTypingLoader(getContextNonNull(), mPackageName);
}
@Override
public void onLoadFinished(@NonNull Loader<ArrayList<TextTypingObject>> loader, @Nullable ArrayList<TextTypingObject> textTypingObjectArrayList) {
if (textTypingObjectArrayList != null && !textTypingObjectArrayList.isEmpty()) {
mTextTypingCustomAdapter = new TextTypingCustomAdapter(getContextNonNull(), textTypingObjectArrayList);
} else {
if (mTextTypingCustomAdapter != null) {
mTextTypingCustomAdapter = null;
}
// ----
if (mPackageName != null && MainActivity.sSelectedPackageName != null) {
mPackageName = null;
MainActivity.sSelectedPackageName = null;
getLoaderManager().restartLoader(1, null, mLoaderCallbacks); // Restart with 1
return;
}
}
// ----
if (mProgressBar != null) {
mProgressBar.setVisibility(View.GONE);
}
if (mTextTypingCustomAdapter != null) {
if (mRecyclerView != null) {
int scrollToPosition = -1;
// ----
if (mItemCount != -1 && mFirstVisibleItemPosition != -1) {
int newItemCount = mTextTypingCustomAdapter.getItemCount();
// ----
if (newItemCount == mItemCount) { // No added/removed events
scrollToPosition = mFirstVisibleItemPosition;
} else if (newItemCount > mItemCount) { // Added events found
if (mFirstVisibleItemPosition != 0) {
int addedEventsCount = newItemCount - mItemCount;
scrollToPosition = mFirstVisibleItemPosition + addedEventsCount;
// ----
if (addedEventsCount >= 1 && mFirstVisibleItemPosition >= 1) {
Snackbar snackbar = Snackbar.make(mView, getContextNonNull().getString(R.string.new_events_found, addedEventsCount) + " (text typing)", Snackbar.LENGTH_SHORT);
snackbar.setAction(getContextNonNull().getString(R.string.scroll), v -> mRecyclerView.smoothScrollToPosition(0));
snackbar.show();
}
}
} else /*if (newItemCount < mItemCount)*/ { // Removed events found
scrollToPosition = mFirstVisibleItemPosition;
}
// ----
mFirstVisibleItemPosition = -1;
mItemCount = -1;
}
// ----
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(mRecyclerView.getContext());
linearLayoutManager.setOrientation(RecyclerView.VERTICAL);
if (scrollToPosition != -1) {
linearLayoutManager.scrollToPosition(scrollToPosition);
}
mRecyclerView.setLayoutManager(linearLayoutManager);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
mRecyclerView.setAdapter(mTextTypingCustomAdapter);
// ----
mRecyclerView.setVisibility(View.VISIBLE);
// ----
}
} else {
if (mScrollView != null) {
mScrollView.setVisibility(View.VISIBLE);
}
}
// ----
if (mPackageName != null) {
mPackageName = null;
}
}
@Override
public void onLoaderReset(@NonNull Loader loader) {
}
}
}

SearchView代码：

@Override
public void onCreateOptionsMenu(@NonNull Menu menu, MenuInflater inflater) {
inflater.inflate(R.menu.typed_text_fragment_menu, menu);
final SearchView searchView = new SearchView(getActivity());
searchView.setQuery(null, true);
searchView.setQueryHint("Search");
EditText searchEditText = searchView.findViewById(androidx.appcompat.R.id.search_src_text);
searchEditText.setTextColor(getResources().getColor(R.color.white));
searchEditText.setHintTextColor(getResources().getColor(R.color.tabTextColor));
searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String s) {
Filter filter = mTextTypingCustomAdapter.getFilter();
if (filter != null) {
filter.filter(s);
return true;
}
return false;
}
@Override
public boolean onQueryTextChange(String s) {
Filter filter = mTextTypingCustomAdapter.getFilter();
if (filter != null) {
filter.filter(s);
return true;
}
return false;
}
});
menu.findItem(R.id.action_search).setActionView(searchView);
}

错误日志：试图在空对象引用上调用虚拟方法"android.widget.Filter-com.app.app.adapter.TextTypeingCustomAdapter.getFilter((">

Answer 1

当你要像这样过滤时

Filter filter = mTextTypingCustomAdapter.getFilter();

如果与任何项不匹配。则变量mTextTypeingCustomAdapter为null。在两种方法(onQueryTextSubmit((&amponQueryTextChange(((

if(mTextTypingCustomAdapter != null){
Filter filter = mTextTypingCustomAdapter.getFilter();}