如何实时从RecyclerView删除条目 [英] How to delete an entry from a RecyclerView in realtime
本文介绍了如何实时从RecyclerView删除条目的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试创建聊天.但是，我面临一个大问题.当我从chat recyclerView删除条目时，该条目保留在那里，但是按预期从firebase数据库中删除了(我的意思是仅从db中删除是可行的).仅当我关闭活动并再次打开它时，它才会消失.我的recyclerView具有每次用户滚动时再加载10个条目的功能.
I am trying to create a chat. However, I am facing a big issue. When I delete an entry from the chat recyclerView, the entry stays there, but is removed from the firebase db as expected (I mean only removing from db is working). It only disapears when I close the activity and open it again. My recyclerView has a feature of load 10 more entries each time a user scrolls.
我不知道如何从recyclerView中删除条目?
I dont understand how can I remove the entry from the recyclerView?
我需要调用函数loadMoreMessages()吗?刷新活动?
I need to call the function loadMoreMessages()? Refresh the activity?
MessageAdapter.java
public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageViewHolder>{
public class MessageViewHolder extends RecyclerView.ViewHolder {
public TextView messageText, displayName;
public CircleImageView profileImage;
public ImageView messageImage;
public MessageViewHolder(View itemView) {
super(itemView);
messageText = (TextView) itemView.findViewById(R.id.message_text_layout);
profileImage = (CircleImageView) itemView.findViewById(R.id.message_profile_layout);
displayName = (TextView) itemView.findViewById(R.id.name_text_layout);
messageImage = (ImageView) itemView.findViewById(R.id.message_image_layout);
}
}
private List<Messages> mMessageList;
private FirebaseAuth mAuth;
private DatabaseReference mUserDatabase;
private DatabaseReference mUserDatabaseSettings;
private String rul, fromUser_t;
private UserAccountSettings mUserAccountSettings;
public MessageAdapter(List<Messages> mMessageList) {
this.mMessageList = mMessageList;
}
@Override
public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.message_single_layout,parent,false);
mAuth = FirebaseAuth.getInstance();
return new MessageViewHolder(v);
}
@Override
public void onBindViewHolder(final MessageViewHolder holder, final int position) {
final String current_user_id = mAuth.getCurrentUser().getUid();
final Messages c = mMessageList.get(position);
final String from_user = c.getFrom();
final String message_type = c.getType();
final String messageContent = c.getMessage();
/**
* popup for text message
*/
// check if the message is from the current user
if(from_user.equals(current_user_id))
{
holder.messageText.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//popup menu to select option
CharSequence options[] = new CharSequence[]
{
"Delete from my phone",
"Delete for Everyone" ,
"Cancel"
};
final AlertDialog.Builder builder = new AlertDialog.Builder(view.getContext());
builder.setTitle("Message Options");
builder.setItems(options, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
//Click Event for each item.
if(i == 0)
{
deleteSentMessage(position, holder);
// Intent intent = new Intent(holder.itemView.getContext(), ChatActivity.class);
// holder.itemView.getContext().startActivity(intent);
//MessageViewHolder.class.notify();
holder.messageText.setPaintFlags(holder.messageText.getPaintFlags() | Paint.STRIKE_THRU_TEXT_FLAG);
}
else if(i == 1)
{
deleteMessageForEveryOne(position, holder);
// Intent intent = new Intent(holder.itemView.getContext(), ChatActivity.class);
// holder.itemView.getContext().startActivity(intent);
//notifyDataSetChanged();
//holder.messageText.setVisibility(View.GONE);
}
}
});
builder.show();
}
});
}else
{
// similar code to check if the message is from the other user
}
holder.messageText.setVisibility(View.GONE);
holder.messageImage.setVisibility(View.GONE);
if("text".equals(message_type))
{
holder.messageText.setVisibility(View.VISIBLE);
if(from_user.equals(current_user_id))
{
holder.messageText.setBackgroundResource(R.drawable.message_text_background);
holder.messageText.setTextColor(Color.WHITE);
//todo left right not working
holder.messageText.setGravity(Gravity.LEFT);
}else
{
holder.messageText.setBackgroundColor(Color.WHITE);
holder.messageText.setTextColor(Color.BLACK);
holder.messageText.setGravity(Gravity.RIGHT);
}
holder.messageText.setText(c.getMessage());
}else
{
holder.messageImage.setVisibility(View.VISIBLE);
UniversalImageLoader.setImage(messageContent,holder.messageImage,null,"");
}
}
@Override
public int getItemCount() {
return mMessageList.size();
}
/**
function to Delete from my phone
**/
private void deleteSentMessage(final int position, final MessageViewHolder holder)
{
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
function to Delete from receiver phone
**/
private void deleteReceiveMessage(final int position, final MessageViewHolder holder)
{
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
/**
function to Delete from both sides
**/
private void deleteMessageForEveryOne(final int position, final MessageViewHolder holder)
{
final DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("messages")
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task)
{
if(task.isSuccessful())
{
rootRef.child("messages")
.child(mMessageList.get(position).getFrom())
.child(mMessageList.get(position).getTo())
.child(mMessageList.get(position).getMessageID())
.removeValue().addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
if(task.isSuccessful())
{
Toast.makeText(holder.itemView.getContext(), "Deleted Successfully.", Toast.LENGTH_SHORT).show();
}
}
});
}else
{
Toast.makeText(holder.itemView.getContext(), "Error Occurred.", Toast.LENGTH_SHORT).show();
}
}
});
}
}
ChatActivity.java
public class ChatActivity extends AppCompatActivity {
private static final String TAG = "ChatActivity";
//todo check is user is logedin
//user with whom Iam talking to
private String mChatUser;
private Toolbar mChatToolbar;
private DatabaseReference mRootRef;
private TextView mTitleView, mLastSeenView;
private CircleImageView mProfileImage;
private FirebaseAuth mAuth;
private String mCurrentUserId;
private ImageButton mChatAddBtn;
private ImageButton mChatSendBtn;
private EditText mChatMessageView;
private RecyclerView mMessagesList;
private SwipeRefreshLayout mRefreshLayout;
private final List<Messages> messagesList = new ArrayList<>();
private LinearLayoutManager mLinearLayout;
private MessageAdapter mAdapter;
private static final int TOTAL_ITEMS_TO_LOAD = 10;
private int mCurrentPage = 1;
private int itemPos =0;
private String mLastKey = "";
private String mPrevKey = "";
private static final int GALLERY_PICK = 1;
//Storage Firebase
private StorageReference mImageStorage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_chat);
// create a toolbar and set the title as the user with we are chatting to
mChatToolbar = (Toolbar) findViewById(R.id.chat_app_bar);
setSupportActionBar(mChatToolbar);
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
// to add a custom view to the toolbar
actionBar.setDisplayShowCustomEnabled(true);
mRootRef = FirebaseDatabase.getInstance().getReference();
mAuth = FirebaseAuth.getInstance();
mCurrentUserId = mAuth.getCurrentUser().getUid();
mChatUser = getIntent().getStringExtra("user_id");
String userName = getIntent().getStringExtra("user_name");
getSupportActionBar().setTitle(userName);
// String userName = getIntent().getStringExtra("user_name");
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View action_bar_view = inflater.inflate(R.layout.chat_custom_bar, null);
actionBar.setCustomView(action_bar_view);
// ---------- Custom Action bar items ---
mTitleView = (TextView) findViewById(R.id.custom_bar_title);
mLastSeenView = (TextView) findViewById(R.id.custom_bar_seen);
mProfileImage = (CircleImageView) findViewById(R.id.custom_bar_image);
mChatAddBtn = (ImageButton) findViewById(R.id.chat_add_btn);
mChatSendBtn = (ImageButton) findViewById(R.id.chat_send_btn);
mChatMessageView = (EditText) findViewById(R.id.chat_message_view);
mAdapter = new MessageAdapter(messagesList);
mImageStorage= FirebaseStorage.getInstance().getReference();
mMessagesList = (RecyclerView) findViewById(R.id.messages_list);
mRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.message_swipe_layout);
mLinearLayout = new LinearLayoutManager(this);
mMessagesList.setHasFixedSize(true);
mMessagesList.setLayoutManager(mLinearLayout);
//mMessagesList.setItemViewCacheSize(25);
mMessagesList.setDrawingCacheEnabled(true);
mMessagesList.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
mMessagesList.setAdapter(mAdapter);
loadMessages();
mTitleView.setText(userName);
mRootRef.child("users").child(mChatUser).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String online = dataSnapshot.child("lastSeen").getValue().toString();
//String image = dataSnapshot.child()
if(online.equals("true")){
mLastSeenView.setText("Online");
}else {
GetTimeAgo getTimeAgo = new GetTimeAgo();
long lastTime = Long.parseLong(online);
String lastSeenTime = getTimeAgo.getTimeAgo(lastTime, getApplicationContext());
mLastSeenView.setText(lastSeenTime);
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
mRootRef.child("Chat").child(mCurrentUserId).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
if(!dataSnapshot.hasChild(mChatUser)){
Map chatAddMap = new HashMap();
chatAddMap.put("seen", false);
chatAddMap.put("timestamp", ServerValue.TIMESTAMP);
Map chatUserMap = new HashMap();
chatUserMap.put("Chat/" + mCurrentUserId + "/" + mChatUser, chatAddMap); //add map to current user
chatUserMap.put("Chat/" + mChatUser + "/" + mCurrentUserId, chatAddMap);
mRootRef.updateChildren(chatUserMap, new DatabaseReference.CompletionListener() {
@Override
public void onComplete(@Nullable DatabaseError databaseError, @NonNull DatabaseReference databaseReference) {
if(databaseError != null){
//Log.d(TAG, "onComplete: CHAT LOG", databaseError.getMessage());
Log.e(TAG, "onComplete: CHAT_LOG" + databaseError.getMessage().toString());
}
}
});
}
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
mChatSendBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sendMessage();
}
});
// open gallery to get an image
mChatAddBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent galleryIntent = new Intent();
galleryIntent.setType("image/*");
galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(galleryIntent,"SELECT IMAGE"), GALLERY_PICK);
}
});
//pagination
mRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
mCurrentPage++;
// each time it loads a new page should go to position zero
itemPos = 0;
loadMoreMessages();
}
});
}
/**
* load more messages everytime uesr refreshes
*/
private void loadMoreMessages() {
DatabaseReference messageRef = mRootRef.child("messages").child(mCurrentUserId).child(mChatUser);
Query messageQuery = messageRef.orderByKey().endAt(mLastKey).limitToLast(10);
messageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages message = dataSnapshot.getValue(Messages.class);
String messageKey = dataSnapshot.getKey();
if(!mPrevKey.equals(messageKey)){
messagesList.add(itemPos++, message);
Log.d(TAG, "onChildAdded: xx" + mPrevKey + "---" + mLastKey);
} else {
mPrevKey = mLastKey;
}
if(itemPos == 1){
mLastKey = messageKey;
}
Log.d(TAG, "onChildAdded: TOTALKEUS" + "lastkey: " + mLastKey + " | Prev key : " + mPrevKey + " | Message Key : " + messageKey);
mAdapter.notifyDataSetChanged();
mRefreshLayout.setRefreshing(false);
mLinearLayout.scrollToPositionWithOffset(itemPos , 0);
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
/**
* method used to load messages once
*/
private void loadMessages() {
//query to get pagination and last 10 messages
DatabaseReference messageRef = mRootRef.child("messages").child(mCurrentUserId).child(mChatUser);
Query messageQuery = messageRef.limitToLast(mCurrentPage * TOTAL_ITEMS_TO_LOAD);
messageQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages message = dataSnapshot.getValue(Messages.class);
itemPos++;
if(itemPos == 1){
// get the key to be user as a start point when loading more items
String messageKey = dataSnapshot.getKey();
mLastKey = messageKey;
mPrevKey = messageKey;
Log.d(TAG, "onChildAdded: last " +mLastKey + " prev " + mPrevKey + " messa " + messageKey + "-----------");
}
messagesList.add(message);
mAdapter.notifyDataSetChanged();
//pagination - define the bottom of the recycler view
//automatic scroll to bottom
mMessagesList.scrollToPosition(messagesList.size() - 1);
mRefreshLayout.setRefreshing(false);
}
@Override
public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
/**
* send photo message
* @param requestCode
* @param resultCode
* @param data
*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == GALLERY_PICK && resultCode == RESULT_OK){
Uri imageUri = data.getData();
final String current_user_ref = "messages/" + mCurrentUserId + "/" + mChatUser;
final String chat_user_ref = "messages/" + mChatUser + "/" + mCurrentUserId;
DatabaseReference user_message_push = mRootRef.child("messages")
.child(mCurrentUserId).child(mChatUser).push();
final String push_id = user_message_push.getKey();
StorageReference filepath = mImageStorage.child("message_images").child( push_id + ".jpg");
filepath.putFile(imageUri).addOnCompleteListener(new OnCompleteListener<UploadTask.TaskSnapshot>() {
@Override
public void onComplete(@NonNull Task<UploadTask.TaskSnapshot> task) {
if(task.isSuccessful()){
Task<Uri> result = task.getResult().getMetadata().getReference().getDownloadUrl();
result.addOnSuccessListener(new OnSuccessListener<Uri>() {
@Override
public void onSuccess(Uri uri) {
String download_url = uri.toString();
Map messageMap = new HashMap();
messageMap.put("message", download_url);
messageMap.put("seen", false);
messageMap.put("type", "image");
messageMap.put("time", ServerValue.TIMESTAMP);
messageMap.put("from", mCurrentUserId);
messageMap.put("to", mChatUser);
messageMap.put("messageID", push_id );
Map messageUserMap = new HashMap();
messageUserMap.put(current_user_ref + "/" + push_id, messageMap);
messageUserMap.put(chat_user_ref + "/" + push_id, messageMap);
mChatMessageView.setText("");
mRootRef.updateChildren(messageUserMap, new DatabaseReference.CompletionListener() {
@Override
public void onComplete(DatabaseError databaseError, DatabaseReference databaseReference) {
if(databaseError != null){
Log.d("CHAT_LOG", databaseError.getMessage().toString());
}
}
});
}
});
}
}
});
}
}
}
``
推荐答案
您正在messageQuery中使用ChildEventListener，该方法具有以下主要方法:
You're using a ChildEventListener in your messageQuery, which has these main methods:
-
onChildAdded，首先对与您的messageQuery查询匹配的每个子节点调用，然后在将任何子节点添加到属于messageQuery的数据库中时调用. -
onChildRemoved，当从数据库中删除任何子节点(跌倒的子节点)(或至少到messageQuery正在侦听的部分)时调用. -
onChildChanged，在数据库中修改任何正在监听messageQuery的子节点时调用.
onChildAdded, which is called initially for every child node matching yourmessageQueryquery, and subsequently when any child node is added to the database that falls intomessageQuery.onChildRemoved, which is called when any child node (that falls) is removed from the database (or at least to the part thatmessageQueryis listening to).onChildChanged, which is called when any child node thatmessageQueryis listening is modified in the database.
如果我看一下您的实现，则您仅实现了onChildAdded.因此，当您从数据库中删除一个子节点时，Firebase会告诉您ChildEventListener关于它的信息，但此后什么也不做.
If I look at your implementation, you've only implemented onChildAdded. So when you remove a child node from the database, Firebase tells your ChildEventListener about it, but that then does nothing.
要在从数据库中删除消息时从UI中删除消息，您将需要实现:
To remove the message from the UI when it gets removed from the database, you will need to implement:
@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
// TODO: remove the message matching dataSnapshot from messagesList
// TODO: call adapter.notifyDataSetChanged() so that the UI gets updates
}
这篇关于如何实时从RecyclerView删除条目的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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