java.lang.NullPointerException: Attempt to read from field 'java.lang.String com.example.g.Model.PersonalShopper.ps_name' on a null object reference

Question

I don't quite sure what when wrong, but I have check the variable name is the same whether it is in a layout xml and the java class, but when I run the apps it give me error which said that

java.lang.NullPointerException: Attempt to read from field 'java.lang.String com.example.g.Model.Ps.ps_name' on a null object reference

I have declare the variable btw.

 firebaseAuth = FirebaseAuth.getInstance();
        currentUser = firebaseAuth.getCurrentUser();
        psID = currentUser.getUid();
        databaseReference = FirebaseDatabase.getInstance().getReference("PersonalShopper").child(firebaseAuth.getUid());

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

                PersonalShopper ps = dataSnapshot.getValue(PersonalShopper.class);
                psname.setText(ps.ps_name);
                pspassword.setText(ps.ps_password);
                psemail.setText(ps.ps_email);

            }

 <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Name"
        android:textSize="13dp"/>

    <EditText
        android:id="@+id/psname"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />


    <TextView
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Password"
        android:textSize="13dp"/>


    <EditText
        android:id="@+id/pspassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />


    <TextView
        android:layout_marginTop="10dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Email"
        android:textSize="13dp"/>

    <TextView
        android:id="@+id/psemail"
        android:hint="email@gmail.com"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

Answer 1

My understanding is that the dataSnapshot is NULL. You should make sure that this variable is not null by lunching your code in debugger and put a breakpoint at this line.

Maybe you could give us a larger scope of your code so we can see where dataSnapshot comes from.

This link may help you..

Answer 2

ps is null:

PersonalShopper ps = dataSnapshot.getValue(PersonalShopper.class);

This means there was no data at the location of the database that you queried. Check your query and the contents of the database to make sure everything is correct.

Answer 3

ps is null: So check if the child have value or not. You can also check the below method it will stop app from crashing and if child value is not null it will show the data.

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

              if (dataSnapshot.exists()){



                PersonalShopper ps = dataSnapshot.getValue(PersonalShopper.class);
                psname.setText(ps.ps_name);
                pspassword.setText(ps.ps_password);
                psemail.setText(ps.ps_email);

            }

             }