在onBindViewHolder侦听器上删除项目时更新回收器视图

Question

我有一个问题，也许我们可以解决它并帮助社区。我为我的RecyclerView制作了一个适配器，并为约束布局创建了一个侦听器，以便删除列表中的一个元素。正如您在代码中看到的，删除消息运行良好，但我不知道如何从AccountFragment(使用此适配器的那个(更新RecyclerView。有人知道如何通知这些变化吗？

AccountFragment:

public class AccountFragment extends Fragment {
private TextView textViewUserProfileUsername;
private TextView textViewUserProfileDescription;
private ImageButton imageButtonAccountEdit;
private EditText editTextAccountDescription;
private RecyclerView recyclerViewUserProfileComments;
private TextView textViewUserProfileNoComments;
private ImageView imageViewUserProfileSendMessage;
private EditText editTextUserProfileSendMessage;
private final Gson gson = new Gson();
private User userLocal;
private SharedPreferences sharedPreferences;
private Context context;
private AlertDialog dialog;
private String previousDescription;
private AccountCommentsAdapter accountCommentsAdapter;
private final List<UserComments> userCommentsList = new ArrayList<>();
public AccountFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
context = getActivity();
assert context != null;
sharedPreferences = context.getSharedPreferences(Constants.sharedPreferencesDocName, Context.MODE_PRIVATE);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_account, container, false);
}
@Override
public void onViewCreated(@NonNull @NotNull View view, @Nullable @org.jetbrains.annotations.Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
bindUI(view);
setListeners();
userLocal = gson.fromJson(sharedPreferences.getString("user", ""), User.class);
showUserInformation();
setAdapter();
}
private void bindUI(View view) {
textViewUserProfileUsername = view.findViewById(R.id.textViewUserProfileUsername);
textViewUserProfileDescription = view.findViewById(R.id.textViewUserProfileDescription);
imageButtonAccountEdit = view.findViewById(R.id.imageButtonAccountEdit);
recyclerViewUserProfileComments = view.findViewById(R.id.recyclerViewUserProfileComments);
textViewUserProfileNoComments = view.findViewById(R.id.textViewUserProfileNoComments);
imageViewUserProfileSendMessage = view.findViewById(R.id.imageViewUserProfileSendMessage);
editTextUserProfileSendMessage = view.findViewById(R.id.editTextUserProfileSendMessage);
}
private void setListeners() {
imageButtonAccountEdit.setOnClickListener(v -> showEditDescriptionDialog());
imageViewUserProfileSendMessage.setOnClickListener(view -> {
if (!TextUtils.isEmpty(editTextUserProfileSendMessage.getText().toString())) {
final Date currentTime = new Date();
@SuppressLint("SimpleDateFormat") SimpleDateFormat simpleDateFormat = new SimpleDateFormat("HH:mm");
TimeZone timeZone = simpleDateFormat.getTimeZone();
simpleDateFormat.setTimeZone(timeZone);
String date = simpleDateFormat.format(currentTime);
final UserComments userCommentsToAdd = new UserComments(userLocal.getId(), userLocal.getId(), userLocal.getUsername(), userLocal.getUsername(), editTextUserProfileSendMessage.getText().toString().trim(), date);
editTextUserProfileSendMessage.setText("");
addComment(userCommentsToAdd);
}
});
}
private void showUserInformation() {
textViewUserProfileUsername.setText(userLocal.getUsername());
textViewUserProfileDescription.setText(userLocal.getDescription());
getUserComments();
}
private void showEditDescriptionDialog() {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle(getString(R.string.edit_description));
final View customLayout = getLayoutInflater().inflate(R.layout.alert_dialog_edit_account, null);
builder.setView(customLayout);
dialog = builder.create();
editTextAccountDescription = customLayout.findViewById(R.id.editTextAccountDescription);
if (userLocal.getDescription() != null) {
editTextAccountDescription.setText(userLocal.getDescription());
previousDescription = editTextAccountDescription.getText().toString();
}
Button buttonAccountCancelDescription = customLayout.findViewById(R.id.buttonAccountCancelDescription);
Button buttonAccountSaveDescription = customLayout.findViewById(R.id.buttonAccountSaveDescription);
buttonAccountSaveDescription.setOnClickListener(v -> saveUserDescription());
buttonAccountSaveDescription.setOnClickListener(v -> {
if (editTextAccountDescription.getText().toString().length() <= 150) {
saveUserDescription();
} else {
setErrors(2);
}
});
editTextAccountDescription.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (s.length() > 150) {
setErrors(2);
}
}
@Override
public void afterTextChanged(Editable s) {
}
});
buttonAccountCancelDescription.setOnClickListener(v -> dialog.dismiss());
dialog.setCancelable(false);
dialog.show();
}
private void saveUserDescription() {
if (!editTextAccountDescription.getText().toString().isEmpty()) {
if (!editTextAccountDescription.getText().toString().equals(previousDescription)) {
userLocal.setDescription(editTextAccountDescription.getText().toString());
sharedPreferences.edit().putString("user", gson.toJson(userLocal)).apply();
Thread thread = new Thread() {
@Override
public void run() {
Response response;
try {
response = UserRequests.editUserDescription(userLocal.getId(), userLocal.getDescription());
if (response.code() == 200) {
String responseBody = Objects.requireNonNull(response.body()).string();
responseBody = responseBody.replace("rn", "");
if (responseBody.contains("1")) {
updateDescription();
} else if (responseBody.contains("2")) {
updateDescription();
} else {
setErrors(1);
}
} else {
setErrors(1);
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
};
thread.start();
} else {
setErrors(4);
}
} else {
setErrors(3);
}
}
private void updateDescription() {
Thread thread = new Thread() {
public void run() {
requireActivity().runOnUiThread(() -> {
textViewUserProfileDescription.setText(userLocal.getDescription());
dialog.dismiss();
});
}
};
thread.start();
}
private void setErrors(int error) {
switch (error) {
case 1:
Thread thread = new Thread() {
public void run() {
requireActivity().runOnUiThread(() -> Toast.makeText(context, getString(R.string.generic_error), Toast.LENGTH_SHORT).show());
}
};
thread.start();
break;
case 2:
editTextAccountDescription.setError(getString(R.string.description_length));
editTextAccountDescription.requestFocus();
break;
case 3:
editTextAccountDescription.setError(getString(R.string.required_field));
editTextAccountDescription.requestFocus();
break;
case 4:
dialog.dismiss();
break;
}
}
private void setAdapter() {
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(context);
linearLayoutManager.setStackFromEnd(true);
recyclerViewUserProfileComments.setLayoutManager(linearLayoutManager);
recyclerViewUserProfileComments.scrollToPosition(userCommentsList.size() - 1);
}
private void displayMessages() {
if (userCommentsList.size() > 0) {
Thread thread = new Thread() {
public void run() {
requireActivity().runOnUiThread(() -> {
if (recyclerViewUserProfileComments.getVisibility() == View.GONE) {
recyclerViewUserProfileComments.setVisibility(View.VISIBLE);
}
if (textViewUserProfileNoComments.getVisibility() == View.VISIBLE) {
textViewUserProfileNoComments.setVisibility(View.GONE);
}
accountCommentsAdapter = new AccountCommentsAdapter(context, userCommentsList);
recyclerViewUserProfileComments.setAdapter(accountCommentsAdapter);
recyclerViewUserProfileComments.scrollToPosition(userCommentsList.size() - 1);
accountCommentsAdapter.notifyDataSetChanged();
});
}
};
thread.start();
} else {
Thread thread = new Thread() {
public void run() {
requireActivity().runOnUiThread(() -> {
recyclerViewUserProfileComments.setVisibility(View.GONE);
textViewUserProfileNoComments.setVisibility(View.VISIBLE);
});
}
};
thread.start();
}
}
private void addComment(UserComments userCommentsToAdd) {
Thread thread = new Thread() {
@Override
public void run() {
Response response;
try {
response = UserCommentsRequests.addUserComment(userCommentsToAdd);
if (response.code() == 200) {
String responseBody = Objects.requireNonNull(response.body()).string();
responseBody = responseBody.replace("rn", "");
if (responseBody.contains("1")) {
userCommentsList.add(userCommentsToAdd);
userCommentsList.clear();
getUserComments();
}
} else if (response.code() == 204) {
displayMessages();
} else {
setErrors(1);
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
};
thread.start();
}
private void getUserComments() {
Thread thread = new Thread() {
@Override
public void run() {
Response response;
try {
response = UserCommentsRequests.getUserComments(userLocal.getId());
if (response.code() == 200) {
String responseBody = Objects.requireNonNull(response.body()).string();
responseBody = responseBody.replace("rn", "");
JSONArray responseArray = new JSONArray(responseBody);
for (int i = 0; i < responseArray.length(); i++) {
String jsonObjectString = responseArray.getJSONObject(i).toString();
userCommentsList.add(gson.fromJson(jsonObjectString, UserComments.class));
}
displayMessages();
} else if (response.code() == 204) {
displayMessages();
} else {
setErrors(1);
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
};
thread.start();
}
}

会计评论适配器：

public class AccountCommentsAdapter extends RecyclerView.Adapter<AccountCommentsAdapter.AccountCommentsAdapterViewHolder> {
private final Context context;
List<UserComments> userCommentsList;
public static final int MSG_TYPE_LEFT = 0;
public static final int MSG_TYPE_RIGHT = 1;
public AccountCommentsAdapter(Context context, List<UserComments> userCommentsList) {
this.context = context;
this.userCommentsList = userCommentsList;
}
@NonNull
@NotNull
@Override
public AccountCommentsAdapterViewHolder onCreateViewHolder(@NonNull @NotNull ViewGroup parent, int viewType) {
View view;
if (viewType == MSG_TYPE_RIGHT) {
view = LayoutInflater.from(context).inflate(R.layout.fragment_chat_message_sent, parent, false);
} else {
view = LayoutInflater.from(context).inflate(R.layout.fragment_chat_message_received, parent, false);
}
return new AccountCommentsAdapterViewHolder(view);
}
@Override
public int getItemViewType(int position) {
FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
assert firebaseUser != null;
if (userCommentsList.get(position).getUser_from_username().equals(firebaseUser.getDisplayName())) {
return MSG_TYPE_RIGHT;
} else {
return MSG_TYPE_LEFT;
}
}
@Override
public void onBindViewHolder(@NonNull @NotNull AccountCommentsAdapterViewHolder holder, int position) {
UserComments userComments = userCommentsList.get(position);
int viewType = holder.getItemViewType();
if (viewType == MSG_TYPE_LEFT) {
holder.textViewMessageUsername.setText(userComments.getUser_from_username());
holder.textViewMessageUsername.setOnClickListener(v -> {
Intent intent = new Intent(context, UserProfileActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
Bundle bundle = new Bundle();
bundle.putString("userId", userComments.getUser_from_id());
bundle.putString("username", userComments.getUser_from_username());
intent.putExtras(bundle);
context.startActivity(intent);
});
holder.constraintLayoutMessageRight.setOnLongClickListener(v -> {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setMessage(R.string.delete_message)
.setPositiveButton(R.string.yes, (dialogInterface, i) -> deleteMessage(position))
.setNegativeButton(R.string.no, (dialogInterface, which) -> dialogInterface.dismiss());
builder.create();
builder.show();
return false;
});
} else {
holder.constraintLayoutMessageRight.setOnLongClickListener(v -> {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setMessage(R.string.delete_message)
.setPositiveButton(R.string.yes, (dialogInterface, i) -> deleteMessage(position))
.setNegativeButton(R.string.no, (dialogInterface, which) -> dialogInterface.dismiss());
builder.create();
builder.show();
return false;
});
}
holder.textViewMessageMessage.setText(userComments.getMessage());
holder.textViewMessageTime.setText(userComments.getCreated_time());
}
@Override
public int getItemCount() {
return userCommentsList.size();
}
public static class AccountCommentsAdapterViewHolder extends RecyclerView.ViewHolder {
ConstraintLayout constraintLayoutMessageRight;
TextView textViewMessageMessage;
TextView textViewMessageTime;
TextView textViewMessageUsername;

public AccountCommentsAdapterViewHolder(@NonNull @NotNull View itemView) {
super(itemView);
textViewMessageMessage = itemView.findViewById(R.id.textViewMessageMessage);
textViewMessageTime = itemView.findViewById(R.id.textViewMessageTime);
constraintLayoutMessageRight = itemView.findViewById(R.id.constraintLayoutMessageRight);
textViewMessageUsername = itemView.findViewById(R.id.textViewMessageUsername);
}
}
private void deleteMessage(int position) {
UserComments userCommentsToRemove = userCommentsList.get(position);
Thread thread = new Thread() {
@Override
public void run() {
Response response;
try {
response = UserCommentsRequests.removeUserComments(userCommentsToRemove.getId());
if (response.code() == 200) {
String responseBody = Objects.requireNonNull(response.body()).string();
responseBody = responseBody.replace("rn", "");
if (responseBody.contains("1")) {
userCommentsList.remove(position);
// Here it should update the recyclerview in order to notify that element has been removed.
}
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
};
thread.start();
}
}

更新：

通过添加此方法解决，然后在userCommentsList.remove(位置(：之后调用它

private void updateUI(){
Handler mainHandler = new Handler(context.getMainLooper());
Runnable runnable = this::notifyDataSetChanged;
mainHandler.post(runnable);
}

Answer 1

在适配器内部，您可以使用notifyDataSetChanged((