Error: com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.sam.simple.Project

Question

I was trying to store user information, for instance a NAME. But I got into some error. Searched and applied methods, but I got errors, logCat is posted below. Can I get a workaround please?

I want to add a new root called "USERS" and user info under that, like a user profile.

But now I just want to add Name of the user.

Below are some codes...

"MY CODE"

        firebaseAuth = FirebaseAuth.getInstance();
    firebaseDatabase = FirebaseDatabase.getInstance();
    databaseReference = firebaseDatabase.getReference();

    authStateListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {

                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {

                Log.d(TAG, "onAuthStateChanged:signed_out");
            }

        }
    };


    databaseReference.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            String value = dataSnapshot.getValue(String.class);

            Log.d(TAG, "Value is: " + value);
        }

        @Override
        public void onCancelled(DatabaseError error) {

            Log.w(TAG, "Failed to read value.", error.toException());
        }
    });


    btn_save_edit_profile.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            String user_name_string = user_name_edit.getText().toString();

            if (!user_name_string.equals("")){
                FirebaseUser user = firebaseAuth.getCurrentUser();
                String userID = user.getUid();

                databaseReference.child(userID).child("Name").setValue(user_name_string);
                Toast.makeText(ProfileEditActivity.this, "Saved Successfully!", Toast.LENGTH_SHORT).show();



            }
        }
    });

LOGCAT

Process: com.sam.simple, PID: 23912

                                       com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.sam.simple.Project
                                                                                    at com.google.android.gms.internal.adw.zzb(Unknown Source)
                                                                                    at com.google.android.gms.internal.adw.zza(Unknown Source)
                                                                                    at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
                                                                                    at com.sam.simple.FirebaseHelper.fetchData(FirebaseHelper.java:52)
                                                                                    at com.sam.simple.FirebaseHelper.access$000(FirebaseHelper.java:14)
                                                                                    at com.sam.simple.FirebaseHelper$1.onChildAdded(FirebaseHelper.java:65)
                                                                                    at com.google.android.gms.internal.uv.zza(Unknown Source)
                                                                                    at com.google.android.gms.internal.aaf.zzIo(Unknown Source)
                                                                                    at com.google.android.gms.internal.aal.run(Unknown Source)
                                                                                    at android.os.Handler.handleCallback(Handler.java:739)
                                                                                    at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                                    at android.os.Looper.loop(Looper.java:145)
                                                                                    at android.app.ActivityThread.main(ActivityThread.java:6918)
                                                                                    at java.lang.reflect.Method.invoke(Native Method)
                                                                                    at java.lang.reflect.Method.invoke(Method.java:372)
                                                                                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
                                                                                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)

OUTPUT WANTED

NOTE: IS IT BECAUSE MY "Project" root is causing any problem? Database maybe pointing towards main root and things? I am new to this. any help? thanks

UPDATE #1: Added My Next Datasnapshot for Projects if this can help any further?

DatabaseReference db;
Boolean saved = null;
ArrayList<Project> projects=new ArrayList<>();

public FirebaseHelper(DatabaseReference db) {
    this.db = db;
}

//WRITE IF NOT NULL
public Boolean save(Project project)
{
    if(project==null)
    {
        saved=false;
    }
    else
    {
        try
        {
            db.child("Project").push().setValue(project);
            saved=true;

        }catch (DatabaseException e)
        {
            e.printStackTrace();
            saved=false;
        }
    }
    return saved;
}

//IMPLEMENT FETCH DATA AND FILL ARRAYLIST
private void fetchData(DataSnapshot dataSnapshot)
{
    projects.clear();
    for (DataSnapshot ds : dataSnapshot.getChildren())
    {
        Project project = ds.getValue(Project.class);
       projects.add(project);
    }
}

//READ THEN RETURN ARRAYLIST
public ArrayList<Project> retrieve() {

    /*Query queryreference = db.orderByChild("postedDate");*/
    /*Query lastToFirstQuery = db.orderByChild("postedDate");*/

    db.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            fetchData(dataSnapshot);

        }
        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
            fetchData(dataSnapshot);
        }
        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {
        }
        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });

    return projects;

Answer 1

Please use this code:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference usersRef = rootRef.child("Users");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String name = ds.child("Name").getValue(String.class);
            Log.d("TAG", name);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
usersRef.addListenerForSingleValueEvent(eventListener);

When you execute a query against the Firebase Database, there will potentially be multiple results. So the snapshot contains a list of those results. Even if there is only a single result, the snapshot will contain a list of one result.