[FIXED] dataSnapshot Not Working "cannot resolve symbol dataSnapshot"

Issue

Hello I am implementing Firebase in my Android Project But it seems that the function dataSnapshot is not being initialized It is being underlined red

Here is the Code for my .java

table_user.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {

        if(dataSnapshot.child(edtphone.getText().toString()).exists()) {

            mDialog.dismiss();
            User user = dataSnapshot.child(edtphone.getText().toString()).getValue(User.class);
            if (user.getPassword().equals(edtpass.getText().toString())) {
                Toast.makeText(signin.this, "Sign In Successful", 
                Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(signin.this, "Sign In Failed", 
                Toast.LENGTH_SHORT).show();
            }
        }
        else
        {
            Toast.makeText(signin.this, "User Not Found", 
            Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError error) {

    }
});

Both of my dataSnapshot functions are not working. I have tried changing it to DataSnapshot but then the .child is not working

Is there an update for this function or a different syntax to try?

Changing to DataSnapshot returns this error

Non-static method 'child(java.lang.String)' cannot be referenced from a static context

Solution

Your onDataChange() has an argument called snapshot and not dataSnapshot, hence that error:

"cannot resolve symbol dataSnapshot"

What you have to do is to change all occurrences of dataSnapshot with snapshot:

  table_user.addValueEventListener(new ValueEventListener() {
                @Override
                                                                //👇
                public void onDataChange(@NonNull DataSnapshot snapshot) {
                       //👇
                    if(snapshot.child(edtphone.getText().toString()).exists()) {

                        mDialog.dismiss();
                                     //👇
                        User user = snapshot.child(edtphone.getText().toString()).getValue(User.class);
                        if (user.getPassword().equals(edtpass.getText().toString())) {
                            Toast.makeText(signin.this, "Sign In Successful", 
                            Toast.LENGTH_SHORT).show();
                        } else {
                            Toast.makeText(signin.this, "Sign In Failed", 
                            Toast.LENGTH_SHORT).show();
                        }
                    }
                    else
                    {
                        Toast.makeText(signin.this, "User Not Found", 
                        Toast.LENGTH_SHORT).show();
                    }
                }

                @Override
                public void onCancelled(@NonNull DatabaseError error) {

                }
            });

The following operation will also not work:

Changing to DataSnapshot returns this error: Non-static method 'child(java.lang.String)' cannot be referenced from a static context

Because the child() method is an instance method and not a static method.

Answered By - Alex Mamo
Answer Checked By - Senaida (JavaFixing Volunteer)