当我使用swipeRefreshLayout从数据库加载所有消息时，发生探测。当我刷新回收站视图时，它将刷新我的第一个密钥，次数与刷新的次数相同。数据仅在回收者视图中以不同的方式查看，不会影响数据库。
如何阻止它在“回收者”视图中多次显示第一个键？任何帮助都将是巨大的，我不知道应该使用什么条件来解决此问题。
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.widget.SwipeRefreshLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.text.TextUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.TextView;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ServerValue;
import com.google.firebase.database.ValueEventListener;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import de.hdodenhof.circleimageview.CircleImageView;
public class MessageActivity extends AppCompatActivity {
// Initialise
private String userID;
private DatabaseReference databaseReference;
private TextView messageTitle;
private TextView lastActive;
private CircleImageView profileImg;
private Toolbar messageToolbar;
private FirebaseAuth firebaseAuth;
private String currentUser;
private EditText messageText;
private ImageButton sendMessage;
// Initialise Array list
private final List<Messages> messages_list = new ArrayList<>();
private LinearLayoutManager linearLayoutManager;
// Messages to load to and current page
private MessageAdapter messageAdapter;
private int current_page = 1;
private static final int messages_to_load = 10;
// Messages RecylerView
private RecyclerView messageView;
private SwipeRefreshLayout swipeRefreshLayout;
private int position = 0;
private String last_message ="";
private String first_message = "";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_message);
// Setup Toolbar
messageToolbar = findViewById(R.id.message_bar);
setSupportActionBar(messageToolbar);
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
actionBar.setDisplayShowCustomEnabled(true);
// Get Database Reference
databaseReference = FirebaseDatabase.getInstance().getReference();
firebaseAuth = FirebaseAuth.getInstance();
currentUser = firebaseAuth.getCurrentUser().getUid();
// Get user ID from Intent
userID = getIntent().getStringExtra("user_ID");
String UserName = getIntent().getStringExtra("user_Name");
// getSupportActionBar().setTitle(UserName);
// Inflater Service
LayoutInflater inflater = (LayoutInflater) this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View message_actionbar_view = inflater.inflate(R.layout.message_custom_imagebar,null);
actionBar.setCustomView(message_actionbar_view);
// Action bar
messageTitle = findViewById(R.id.message_bar_title);
lastActive = findViewById(R.id.message_bar_lastseen);
profileImg = findViewById(R.id.message_image);
messageText = findViewById(R.id.send_message_text);
sendMessage = findViewById(R.id.message_send_btn);
messageAdapter = new MessageAdapter(messages_list);
messageView = findViewById(R.id.Messages_recycler);
// set swipe layout
swipeRefreshLayout = findViewById(R.id.swipe_layout_message);
linearLayoutManager = new LinearLayoutManager(this);
messageView.setHasFixedSize(true);
messageView.setLayoutManager(linearLayoutManager);
messageView.setAdapter(messageAdapter);
// Call get messages method
getMessages();
// Set values
messageTitle.setText(UserName);
databaseReference.child("Users").child(userID).addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String onlineUser = dataSnapshot.child("online").getValue().toString();
String userImg = dataSnapshot.child("image").toString();
Timestamp timestamp = new Timestamp();
long lastSeen = Long.parseLong(onlineUser);
String lastActives = timestamp.getTimeAgo(lastSeen, getApplicationContext());
// lastActive.setText(lastActives);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
// click event on image button
sendMessage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sendMessageText();
}
});
// What happens when you swipe to refresh
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
@Override
public void onRefresh() {
current_page++;
position = 0;
getAllMessages();
}
});
}
// Load a number of messages
private void getAllMessages() {
DatabaseReference message_reference = databaseReference.child("Messages").child(currentUser).child(userID);
Query message_Query = message_reference.orderByKey().endAt(last_message).limitToLast(10);
message_Query.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages message = dataSnapshot.getValue(Messages.class);
String last_message_key = dataSnapshot.getKey();
messages_list.add(position++, message);
// Checks if position is 1
if(position == 1){
last_message = last_message_key;
}
messageAdapter.notifyDataSetChanged();
swipeRefreshLayout.setRefreshing(false);
linearLayoutManager.scrollToPositionWithOffset(10,0);
}
@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) {
}
});
}
private void getMessages() {
DatabaseReference message_reference = databaseReference.child("Messages").child(currentUser).child(userID);
Query message_Query = message_reference.limitToLast(current_page * messages_to_load);
message_Query.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Messages messages = dataSnapshot.getValue(Messages.class);
position++;
if(position == 1){
String last_message_key = dataSnapshot.getKey();
last_message = last_message_key;
first_message = last_message_key;
}
messages_list.add(messages);
messageAdapter.notifyDataSetChanged();
messageView.scrollToPosition(messages_list.size() - 1);
swipeRefreshLayout.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) {
}
});
}
private void sendMessageText() {
String message = messageText.getText().toString();
if(!TextUtils.isEmpty(message)){
String current_User = "Messages/" + currentUser + "/" + userID;
String chat_User = "Messages/" + userID + "/" + currentUser;
DatabaseReference message_push = databaseReference.child("Messages").child(currentUser).child(userID).push();
String pushID = message_push.getKey();
Map sendMessageMap = new HashMap();
sendMessageMap.put("message", message);
sendMessageMap.put("seen", false);
sendMessageMap.put("type", "text");
sendMessageMap.put("time", ServerValue.TIMESTAMP);
sendMessageMap.put("from", currentUser);
Map sendUserMap = new HashMap();
sendUserMap.put(current_User + "/" + pushID, sendMessageMap);
sendUserMap.put(chat_User + "/" + pushID, sendMessageMap);
messageText.setText("");
databaseReference.updateChildren(sendUserMap, new DatabaseReference.CompletionListener() {
@Override
public void onComplete(@Nullable DatabaseError databaseError, @NonNull DatabaseReference databaseReference) {
if(databaseError != null){
Log.d("CHAT_LOG", databaseError.getMessage());
}
}
});
}
}
}
它应该只打印一次以供回收者查看，而不是2或3次。