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我的应用正在将用户保存在my firebase database中,但是当我尝试读取对象的值时,它始终返回null。我的firebase的规则都是真实的,应用程序正在保存用户。我不知道为什么我不能读取数据,为什么它总是返回null。这是我的MainActivity类别:从Firebase数据库检索数据为空
package com.example.leo_o.testfirebase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
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;
public class MainActivity extends AppCompatActivity implements
View.OnClickListener {
private Button saveButton;
private EditText nameEditText;
private DatabaseReference mDatabase;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDatabase = FirebaseDatabase.getInstance().getReference("users");
saveButton = (Button) findViewById(R.id.saveButton);
nameEditText = (EditText) findViewById(R.id.nameEditText);
}
private void saveUser(String name) {
User user = new User(name);
String userId = mDatabase.push().getKey();
mDatabase.child(userId).setValue(user);
}
public void getData() {
ValueEventListener userListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
String name = user.getName();
if (name == null) {
Toast.makeText(MainActivity.this, "Null value", Toast.LENGTH_SHORT).show();
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
mDatabase.addValueEventListener(userListener);
}
@Override
public void onClick(View view) {
if (view == saveButton) {
String name = nameEditText.getText().toString();
saveUser(name);
getData();
}
}
}
的,这是我的用户等级:
package com.example.leo_o.testfirebase;
public class User {
public String name;
public User() {
}
public User(String name) {
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
有谁知道什么是错我的代码,为什么它总是返回null?