Retrieving data from firebase database in android

Question

I'm recently migrated to Firebase. I have gone through Firebase Android api docs for retrieving data from database through JSON. there is method onDataChange(DataSnapshot snapshot) to retrieve data whenever there is change in data in database but I could find how to retrieve data even if there is no change in database.

For example:- when a user logs into my app, I want that data which is stored under the unique id node should be retrieved. How can I retrieve data anytime from Firebase database if i want?

if you want retrieve data from firebase, just create a reference object of your desired firebase path. Firebase ref=new Firebase(path); — Narendra Baratam
– Narendra Baratam, Commented Mar 8, 2016 at 8:31

Frank van Puffelen · Accepted Answer · 2016-03-07 16:28:16Z

2

From the Firebase guide on reading data:

[the onDataChange() method is] triggered once with the initial data and again every time the data changes.

I highly recommend that you read the Firebase guide for Android programming end-to-end. It'll answer many of the questions you're likely to have as you start using Firebase.

answered Mar 7, 2016 at 16:28

Frank van Puffelen

603k85 gold badges895 silver badges869 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

viral 9966 · Accepted Answer · 2017-07-26 13:35:01Z

Firebase Read and Write Database Guide lines: https://firebase.google.com/docs/database/android/read-and-write

public class NavigationActivity extends AppCompatActivity{
private DatabaseReference mDatabase;
    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener mAuthListener;
 @Override
    protected void onStart() {
        super.onStart();
        mAuth.addAuthStateListener(mAuthListener);
    }


 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

initializeAuthListener();

 mDatabase = FirebaseDatabase.getInstance().getReference();



}

private void initializeAuthListener() {
        mAuth = FirebaseAuth.getInstance();
        mAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                firebaseUser = firebaseAuth.getInstance().getCurrentUser();
                try {
                    if (firebaseAuth != null) {
                        loadUserDetails();
                        Log.d("@@@@", "thread:signed_in:" + firebaseUser.getUid());
                    } else {
                        Log.d("@@@@", "thread:signed_out");
                        Intent login = new Intent(NavigationActivity.this, LoginActivity.class);
                        startActivity(login);
                        finish();
                    }
                }catch (Exception e){
                    Intent login = new Intent(NavigationActivity.this, LoginActivity.class);
                    startActivity(login);
                    finish();
                }

            }
        };
        mAuth.addAuthStateListener(mAuthListener);
    }

private void loadUserDetails() {
        DatabaseReference userReference = mDatabase
                .child("users").child(firebaseUser.getUid());

//        displayUserDetails(userReference);
        userReference.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                user = dataSnapshot.getValue(User.class);

                tv_user_name.setText(user.getDisplayName());
                tv_user_email_nav.setText(user.getEmail());

                Glide.with(NavigationActivity.this)
                        .load(user.getPhotoUrl())
                        .placeholder(R.mipmap.profile)
                        .centerCrop()
                        .dontAnimate()
                        .bitmapTransform(new CropCircleTransformation(NavigationActivity.this))
                        .into(iv_user_image);

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
//                Toast.makeText(ThreadActivity.this, R.string.error_loading_user, Toast.LENGTH_SHORT).show();
//                finish();
            }
        });
    }
}

https://stackoverflow.com/a/45328201/5973946

Collectives™ on Stack Overflow

Retrieving data from firebase database in android

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related