CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
KSUERS
KSUERS

Reputation: 589

java.lang.NullPointerException (firebase)

my app shut down after login, I don't know why?

this is a part of the code from the profile page, after the user login it should go to this page :

public class profilepage extends AppCompatActivity {
 TextView inputFullname;
    TextView uniemail;
    FirebaseAuth mAuth;
    FirebaseUser mUser;

    DatabaseReference mRefUser, RootRef, mUserOldRef;
    String userEmail, userID, userName;


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

 mRefUser = FirebaseDatabase.getInstance().getReference().child("Profile");
        mUserOldRef = FirebaseDatabase.getInstance().getReference().child("users");
        RootRef = FirebaseDatabase.getInstance().getReference();
        mAuth = FirebaseAuth.getInstance();
        mUser = mAuth.getCurrentUser();

 inputFullname = findViewById(R.id.profileName);
        uniemail = findViewById(R.id.profileEmail);

        LoadUserProfile();


    private void LoadUserProfile() {
    
    
            mUserOldRef.child(mUser.getUid()).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(@NonNull DataSnapshot snapshot) {
    
                    userName = snapshot.child("userName").getValue().toString();
                    inputFullname.setText(userName);
    
                    userEmail = snapshot.child("userEmail").getValue().toString();
                    uniemail.setText(userEmail);
                }
    
                @Override
                public void onCancelled(@NonNull DatabaseError error) {
    
                }
            });
    
    
        }

the error is :

 Process: com.example.ksuersapp, PID: 10342
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.Object.toString()' on a null object reference
        at com.example.ksuersapp.profilepage$6.onDataChange(profilepage.java:200)
        at com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75)
        at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
        at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

any idea what I can do to solve the problem? the mean idea of the code is to retrieve the information about the user from the firebase Realtime database

Upvotes: 0

Views: 60

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 600100

It looks like no user information exists at the location you're trying to read. To handle this situation in your code, check whether the snapshot exists:

mUserOldRef.child(mUser.getUid()).addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
      if (snapshot.exists()) {
        userName = snapshot.child("userName").getValue().toString();
        inputFullname.setText(userName);

        userEmail = snapshot.child("userEmail").getValue().toString();
        uniemail.setText(userEmail);
      }
      else {
        Log.i("Database", "No user info exists for "+mUser.getUid());
      }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError error) {
        throw error.toException(); // never ignore errors
    }
});

Upvotes: 1

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