Question

I want to get user's name from my firebase database but I'm getting this error

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference

here is my firebase database structure:

below is my code which is proffering the same error:

public class MyAccount extends AppCompatActivity {

private Button mSetupButton;
private EditText mSetupName;
private EditText mSetupBio;
private ImageButton mSetupImageButton;
private FirebaseAuth mAuth;
private FirebaseAuth.AuthStateListener mAuthListener;
private String mPostKey=null;
private DatabaseReference mDatabase;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my_account);

    mAuth=FirebaseAuth.getInstance();
    String user_id=mAuth.getCurrentUser().getUid();

    mDatabase= FirebaseDatabase.getInstance().getReference().child("Profiles");
    mPostKey=getIntent().getExtras().getString(user_id);

    mSetupName = (EditText) findViewById(R.id.accountName);
    mSetupBio = (EditText) findViewById(R.id.accountBio);
    mSetupButton = (Button) findViewById(R.id.accountButton);
    mSetupImageButton = (ImageButton) findViewById(R.id.accountImageButton);


    mDatabase.child(mPostKey).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            String post_name = (String) dataSnapshot.child("Name").getValue();
            mSetupName.setText(post_name);

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}

}

Apparently the error is in getting user id.

Answer 1

just update or add as per your naming convention and your requirements in FirstScreen(i have almost done the required changes you need to make).

 Intent i = new Intent(FirstScreen.this, MyAccount.class);   
 String user_id;
 i.putExtra("user_id", user_id);

Answer 2

假设之前的活动是MainActivity，那么这是将额外的活动加到意图

的代码

String mPostKey = // the post key value here

Intent intent = new Intent(MainActivity.this, MyAccount.class);
intent.putExtra("post_key", mPostKey);
startActivity(intent);

要在MyAccount活动中获得额外费用，请致电

mPostKey = getIntent().getExtras().getString("post_key");

顺便说一句，我建议您通过将uid作为“post key”来更改数据库结构，这样您就可以更轻松地读取用户的信息而无需检索“post key”< / p>

{
    "profiles": {
        "0059HUGgfNcEyX73ZpTi6HQUscu1": {
            "email": "aaa@gmail.com",
            "image": "...",
            "name": "...",
            "phone": "..."
        },
        "other user's uid": {
            ...
        }
    }
}

使用这种数据库结构，您不再需要mPostKey（不需要放置并获得额外的意图）。要获取用户的信息，您可以执行此操作

mDatabase.child(mAuth.getCurrentUser().getUid()). addValueEventListener(eventListener);

希望我的回答有所帮助：）

Answer 3

要从firebase获取当前登录用户的名称，只需使用以下代码：

String user_name=mAuth.getCurrentUser().getDisplayName();

I want to get Name of currently logged in user from firebase

3 个答案: