我有2个活动。 MainActivity有一个注释列表，secondActivity单独显示它们。问题是，当我单击MainActivity中的注释之一时，它将转到secondActivity，但是当我单击“后退”按钮时，secondActivity将打开。经过4-5次尝试后，我到达了MainActivity。导航工作正常，但我不知道它突然中断了。
MainActivity：
public class MainActivity extends AppCompatActivity{
private StaggeredGridLayoutManager gridLayoutManager;
private RecyclerView recyclerView;
private List<Note> noteList, multiSelectList, filteredList;
public NotesAdapter notesAdapter;
private Notedatabase notedatabase;
private String TAG = MainActivity.class.getSimpleName();
private FloatingActionButton maddbtn;
private int position;
private SearchView mSearchView;
private boolean isMultiSelect = false;
private Menu context_menu;
private ActionMode mActionMode;
private CoordinatorLayout mCoordinatorLayout;
private RelativeLayout mEmptyContainer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initViews();
displayList();
/*
notesList.addAll(noteList);
List<Note> notesList = getNotes();
notesAdapter = new NotesAdapter(notesList,MainActivity.this);
recyclerView.setAdapter(notesAdapter);
*/
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.menu,menu);
// Searchable config with searchview
SearchManager manager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
mSearchView = (SearchView) menu.findItem(R.id.action_search).getActionView();
mSearchView.setSearchableInfo(manager.getSearchableInfo(getComponentName()));
mSearchView.setMaxWidth(Integer.MAX_VALUE);
// Set Listener
mSearchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
@Override
public boolean onQueryTextSubmit(String query) {
// filter when query is submitted
Log.d(TAG, "onQueryTextSubmit: " + query);
filteredList = filter(newText, noteList);
notesAdapter.filterList(filteredList);
if (filteredList.isEmpty()) displayEmptyState();
return false;
}
@Override
public boolean onQueryTextChange(String newText) {
// filter progressively as query changes
Log.d(TAG, "onQueryTextChange: " + newText);
if(!newText.isEmpty() && mEmptyContainer.getVisibility() == View.VISIBLE)
mEmptyContainer.setVisibility(View.GONE);
if(newText.isEmpty() && mEmptyContainer.getVisibility() == View.VISIBLE) {
Log.d(TAG, "Empty query");
mEmptyContainer.setVisibility(View.GONE);
// Close the keyboard
mSearchView.post(new Runnable() {
@Override
public void run() {
mSearchView.clearFocus();
if(!mSearchView.isIconified())
mSearchView.setIconified(true);
}
});
}
filteredList = filter(newText, noteList);
notesAdapter.filterList(filteredList);
if (filteredList.isEmpty()) displayEmptyState();
return false;
}
});
mSearchView.setOnCloseListener(new SearchView.OnCloseListener() {
@Override
public boolean onClose() {
if(mEmptyContainer.getVisibility() == View.VISIBLE) mEmptyContainer.setVisibility(View.GONE);
return false;
}
});
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if(item.getItemId() == R.id.action_search) {
// search action
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onBackPressed() {
// close searchview
if(!mSearchView.isIconified()) {
// Clears the text
mSearchView.setIconified(true);
mSearchView.onActionViewCollapsed();
refreshAdapter();
if(mEmptyContainer.getVisibility() == View.VISIBLE) mEmptyContainer.setVisibility(View.GONE);
}
else super.onBackPressed();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(requestCode == REQUEST_CODE) {
if (resultCode == 1) {
Log.d(TAG, "Request code is 1");
noteList.add((Note) data.getSerializableExtra("note"));
notesAdapter.notifyDataSetChanged();
//displayList();
}
else if(resultCode == 2) {
Log.d(TAG, "Request code 2, update return");
noteList.set(position, (Note) data.getSerializableExtra("note"));
notesAdapter.notifyDataSetChanged();
}
else if(resultCode == 3) {
Log.d(TAG, "Request code 3, delete return");
Log.d(TAG, "Deleting this from list:" + (Note) data.getSerializableExtra("note"));
noteList.remove(MainActivity.this.position);
notesAdapter.notifyItemRemoved(MainActivity.this.position);
if(noteList.isEmpty()) displayEmptyState();
}
}
}
private void displayList() {
notedatabase = Notedatabase.getInstance(MainActivity.this);
new RetrieveTask(this).execute();
}
private void initViews() {
recyclerView = findViewById(R.id.recyclerview);
gridLayoutManager = new StaggeredGridLayoutManager(2,1);
mCoordinatorLayout = findViewById(R.id.coordinatorLayout);
mEmptyContainer = findViewById(R.id.empty_container);
recyclerView.setLayoutManager(gridLayoutManager);
noteList = new ArrayList<>();
multiSelectList = new ArrayList<>();
notesAdapter = new NotesAdapter(noteList,MainActivity.this,multiSelectList);
recyclerView.setAdapter(notesAdapter);
maddbtn = findViewById(R.id.add_fab);
maddbtn.setOnClickListener(v -> {
Intent intent = new Intent(MainActivity.this,NoteActivity.class);
startActivityForResult(intent,REQUEST_CODE);
});
}
/*
@Override
public void onClick(View view, int pos) {
Log.d(TAG, "Recylerview item onClick: ");
MainActivity.this.position = pos;
Intent intent = new Intent(MainActivity.this,NoteActivity.class);
intent.putExtra("note",noteList.get(position));
Log.d(TAG, "list.get(position): " + noteList.get(pos).getDesc());
startActivityForResult(intent,REQUEST_CODE);
}
*/
/* @Override
public void onClick(Note note) {
Log.d(TAG, "onClick with args as note1");
Intent intent = new Intent(MainActivity.this,NoteActivity.class);
intent.putExtra("note",note);
startActivityForResult(intent,REQUEST_CODE);
}
*/
/*
@Override
public void onLongClick(View view, int pos) {
Log.d(TAG, "onLongClick ");
if(!isMultiSelect) {
multiSelectList = new ArrayList<Note>();
isMultiSelect = true;
if(mActionMode == null) {
mActionMode = startActionMode(mActionModeCallback);
}
}
multi_select(pos);
}
*/
private void multi_select(int pos) {
if(mActionMode != null) {
if(multiSelectList.contains(noteList.get(pos))) {
Log.d(TAG, "multi_select removed: " + multiSelectList.contains(noteList.get(pos)));
multiSelectList.remove(noteList.get(pos));
}
else {
Log.d(TAG, "multi_select added: " + multiSelectList.contains(noteList.get(pos)));
multiSelectList.add(noteList.get(pos));
}
if(multiSelectList.size() > 0) mActionMode.setTitle("" + multiSelectList.size() + " selected");
else mActionMode.setTitle("");
refreshAdapter();
}
}
private void refreshAdapter() {
notesAdapter.selectednotes_list = multiSelectList;
notesAdapter.list = noteList;
notesAdapter.notifyDataSetChanged();
}
class RetrieveTask extends AsyncTask<Void,Void,List<Note>>{
private WeakReference<MainActivity> weakReference;
public RetrieveTask(MainActivity mainActivity) {
weakReference = new WeakReference<>(mainActivity);
}
@Override
protected List<Note> doInBackground(Void... voids) {
if(weakReference.get()!=null)
return weakReference.get().notedatabase.getNoteDao().getNotes();
else
return null;
}
@Override
protected void onPostExecute(List<Note> notes) {
if(notes!=null & notes.size()>0) {
if(mEmptyContainer.getVisibility() == View.VISIBLE) mEmptyContainer.setVisibility(View.GONE);
weakReference.get().noteList = notes;
weakReference.get().filteredList = noteList;
//weakReference.get().noteList.addAll(weakReference.get().getNotes());
Log.d(TAG, "Result: " + notes);
weakReference.get().notesAdapter = new NotesAdapter(notes,weakReference.get(),multiSelectList);
/*
// Randomly set note background
for(Note n:notes) {
n.setColor(getRandomMaterialColor(MainActivity.this,"500"));
}
*/ weakReference.get().recyclerView.addOnItemTouchListener(new RecyclerTouchListener(recyclerView, getApplicationContext(), new ClickListener() {
@Override
public void onClick(View view, int pos) {
if (isMultiSelect)
multi_select(pos);
else {
Log.d(TAG, "Recylerview item onClick: ");
MainActivity.this.position = pos;
Intent intent = new Intent(MainActivity.this, NoteActivity.class);
intent.putExtra("note",filteredList.get(pos).get(pos));
Log.d(TAG, "pos: " + pos);
Log.d(TAG, "list.get(position): " + weakReference.get().filteredList.get(pos).get(position).getDesc());
startActivityForResult(intent, REQUEST_CODE);
}
}
@Override
public void onClick(View view) {
Log.d(TAG, "onClick with args as note");
Intent intent = new Intent(MainActivity.this, NoteActivity.class);
intent.putExtra("note", noteList.get(recyclerView.getChildAdapterPosition(view)));
startActivityForResult(intent, REQUEST_CODE);
}
@Override
public void onLongClick(View view, int pos) {
Log.d(TAG, "onLongClick ");
if(!isMultiSelect) {
multiSelectList = new ArrayList<Note>();
isMultiSelect = true;
if(mActionMode == null) {
mActionMode = startActionMode(mActionModeCallback);
}
}
multi_select(pos);
}
}));
weakReference.get().recyclerView.setAdapter(weakReference.get().notesAdapter);
weakReference.get().notesAdapter.notifyDataSetChanged();
}
else{
// empty state
displayEmptyState();
}
}
}
private void displayEmptyState() {
mEmptyContainer.setVisibility(View.VISIBLE);
}
private ActionMode.Callback mActionModeCallback = new ActionMode.Callback() {
@Override
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
//Prepare the menu
MenuInflater inflater = mode.getMenuInflater();
inflater.inflate(R.menu.contextual_action,menu);
context_menu = menu;
return true;
}
@Override
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
//mode.getCustomView().setBackgroundColor(getApplicationContext().getResources().getColor(android.R.color.white));
return false;
}
@Override
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
switch (item.getItemId()) {
case R.id.action_delete:
// display alert dialog
AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
builder.setMessage("Delete " + multiSelectList.size() + " notes?");
builder.setCancelable(true);
builder.setPositiveButton(R.string.alert_yes,(dialog, which) -> {
// Deleting notes
for (int i = 0; i < multiSelectList.size(); i++) {
Log.d(TAG, "Deleting: " + multiSelectList.get(i));
notedatabase.getNoteDao().deleteNotes(multiSelectList.get(i));
noteList.remove(multiSelectList.get(i));
}
// Display Snackbar
displaySnackbar(mCoordinatorLayout,R.string.delete_success);
dialog.cancel();
// Refresh adapter
refreshAdapter();
// dismiss the contextual action bar
if(mActionMode!=null) mActionMode.finish();
// check for empty state
if(noteList.isEmpty()) displayEmptyState();
});
builder.setNegativeButton(R.string.alert_no,(dialog, which) -> {
dialog.cancel();
if(mActionMode!=null) mActionMode.finish();
});
builder.setOnCancelListener(dialog1 -> {
Log.d(TAG, "onCancelListener: ");
if(mActionMode!=null) mActionMode.finish();
});
AlertDialog dialog = builder.create();
dialog.show();
return true;
default:
return false;
}
}
@Override
public void onDestroyActionMode(ActionMode mode) {
mActionMode = null;
isMultiSelect = false;
multiSelectList = new ArrayList<Note>();
refreshAdapter();
}
};
@Override
protected void onDestroy() {
notedatabase.cleanUp();
super.onDestroy();
}
}
SecondActivity：
public class NoteActivity extends AppCompatActivity {
EditText mtext;
//FloatingActionButton mfab;
OptionsFabLayout fab_menu;
CoordinatorLayout mCoordinatorLayout;
private String TAG = NoteActivity.class.getSimpleName();
private NoteDao note_dao; // Sql access object
private Note temp_note; //Used for creating a note
public Notedatabase notedatabase;
private boolean update = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_note);
mtext = findViewById(R.id.note_text);
fab_menu = findViewById(R.id.fab);
mCoordinatorLayout= findViewById(R.id.coordinatorLayout);
notedatabase = Notedatabase.getInstance(NoteActivity.this);
if((temp_note = (Note)getIntent().getSerializableExtra("note"))!=null) {
update = true;
mtext.setText(temp_note.getDesc());
}
fab_menu.setMainFabOnClickListener( v -> {
if(fab_menu.isOptionsMenuOpened()) fab_menu.closeOptionsMenu();
});
fab_menu.setMiniFabSelectedListener(fabItem -> {
switch(fabItem.getItemId()) {
case R.id.fab_save:
// Call update method of DAO
if (update) {
temp_note.setDesc(mtext.getText().toString());
temp_note.setTime(getDate());
notedatabase.getNoteDao().Update(temp_note);
setResult(temp_note, 2);
} else {
// Insert
if (TextUtils.isEmpty(mtext.getText().toString())) {
displaySnackbar(mCoordinatorLayout, R.string.empty_insert);
} else {
temp_note = new Note(mtext.getText().toString(), getDate());
Log.d(TAG, "Inserting values as : " + temp_note.getId() + temp_note.getDesc() + temp_note.getTime());
new InsertTask(NoteActivity.this, temp_note).execute();
}
}
break;
case R.id.fab_delete:
// Delete
if(TextUtils.isEmpty(mtext.getText().toString())) {
displaySnackbar(mCoordinatorLayout,R.string.empty_insert);
}
if ((temp_note = (Note) getIntent().getSerializableExtra("note")) != null) {
displayAlert(NoteActivity.this, temp_note);
}
break;
case R.id.fab_share:
// Share
getShareIntent(NoteActivity.this, temp_note);
break;
}
});
}
public void displayAlert(Context context, Note note) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setMessage(R.string.alert_message);
builder.setCancelable(true);
builder.setPositiveButton(R.string.alert_yes,(dialog, which) -> {
// Delete note
Log.d(TAG, "Deleting values :" + note.getDesc() + note.getTime());
notedatabase.getNoteDao().delete(note);
displaySnackbar(mCoordinatorLayout,R.string.delete_success);
setResult(note, 3);
dialog.cancel();
});
builder.setNegativeButton(R.string.alert_no,(dialog, which) -> {
dialog.cancel();
});
AlertDialog dialog = builder.create();
dialog.show();
}
@Override
public void onBackPressed() {
if(fab_menu.isOptionsMenuOpened()) fab_menu.closeOptionsMenu();
super.onBackPressed();
}
public void setResult(Note note, int flag) {
setResult(flag , new Intent().putExtra("note",note));
finish();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(resultCode==1) {
Snackbar.make(mCoordinatorLayout,R.string.success_insert,Snackbar.LENGTH_SHORT).show();
}
else
Snackbar.make(mCoordinatorLayout,R.string.failure_insert,Snackbar.LENGTH_SHORT).show();
}
}
答案 0 :(得分：0)
我认为它被调用了多次，因为每次用户按下返回键时，您都会调用displayList方法。在该方法内，您调用.addOnItemTouchListener将新的侦听器添加到回收视图，直到条件!mSearchView.isIconified()为true。
为避免这种情况，您应该在.addOnItemTouchListener方法中仅onCreate调用一次 。
答案 1 :(得分：0)
我想我已经解决了。事情是AFAIK，我将过滤器列表存储在原始列表noteList中。我添加了一个新列表filteredList，初始化为noteList，但存储了过滤器的结果。结果，现在我不需要每次回到原始状态时都调用displayList（）了。另外，以前我每当退格一个char时，它都不会显示出增加的结果，现在也可以了。 根据更改更新了代码