实时数据Firebase数据库出现问题

Question

我正试图从具有以下结构的数据库中检索所有uid。该图像显示了"；用户"；"；uid"；的子项，其中username和value作为username我无法访问数据库。

package com.example.androidChat;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.Toast;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
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.ValueEventListener;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
ListView userListView;
ArrayList<String> UsernameArrayList, UidArrayList;
private FirebaseAuth mAuth;
FirebaseDatabase database;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAuth = FirebaseAuth.getInstance();
userListView = findViewById(R.id.userListView);
UsernameArrayList = new ArrayList<>();
UidArrayList = new ArrayList<>();
database = FirebaseDatabase.getInstance();
DatabaseReference getUser = database.getReference().child("User");
getUser.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot snapshot) {
for (DataSnapshot dataSnapshot: snapshot.getChildren()){
Log.i("Users", dataSnapshot.getValue().toString());
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Log.i("Users", "Error over here!!");
Log.w("Error: ", error.getMessage());
}
});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater menuInflater = getMenuInflater();
menuInflater.inflate(R.menu.main_menu,menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.logout:
newGame();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
private void newGame() {
mAuth = FirebaseAuth.getInstance();
mAuth.signOut();
Intent intent = new Intent(this, StartActivity.class);
startActivity(intent);
}
}

我尝试添加一些依赖项，并尝试了所有操作，但出现了以下错误。

implementation 'com.google.android.gms:play-services-basement:17.4.0'

上一行是在另一个问题中提出的建议，但没有奏效。

2020-12-13 15:46:38.426 8679-9347/com.example.androidChat W/ConnectionTracker: Exception thrown while unbinding
java.lang.IllegalArgumentException: Service not registered: lt@e163c21
at android.app.LoadedApk.forgetServiceDispatcher(LoadedApk.java:1466)
at android.app.ContextImpl.unbindService(ContextImpl.java:1622)
at android.content.ContextWrapper.unbindService(ContextWrapper.java:697)
at ci.f(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):1)
at ci.d(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):2)
at lu.E(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):9)
at le.a(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):3)
at eg.run(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):3)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:457)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at iz.run(:com.google.android.gms.dynamite_measurementdynamite@204713052@20.47.13 (040700-0):5)

我甚至尝试更改模拟器并在自己的设备上运行它。

Answer 1

检查是否添加了最新的Firebase实时数据库依赖项-https://firebase.google.com/docs/android/setup

com.google.firebase:firebase-database:19.5.1

检查您的依赖关系是否已同步。

检查您的realtime database是否有permissions可以访问数据，read/write可以访问数据而不是authenticated。

通过检查firebase console，检查您的firebase应用程序是否正确集成到android应用程序

尝试使缓存无效并启动Android Studio。