Super Class Reference on member variable and method - oop

Question

public class ClassA {
int value = 50;
public void display(){
System.out.println("ClassA displaying value:"+ value);
}
}
public class ClassB extends ClassA {
int value = 25;
public void display(){
System.out.println("ClassB displaying value:"+ value);
}
}
public class Test {
public static void main(String[] args) {
ClassA objA = new ClassB();
ClassB objB = new ClassB();
System.out.println(objA.value); --> 50
System.out.println(objB.value); --> 25
objA.display(); --> ClassA Displaying value: 25
objB.display(); --> ClassB Displaying value: 25
}
}
can somebody explain why objA is printing superclass value 50.
In method overriding, at Compile time the object reference is ClassA and it looks for a method Display() in ClassA. If that method is available at ClassA then at runtime actual object created is of ClassB and display() method in ClassB overrides ClassA 's display() method.
But what is happening when we printing the class property "Value" ?
ClassA objA = new ClassB();
System.out.println(objA.value);
Here reference is ClassA and actual object is of ClassB. So I am expecting classB's value: 25. But the value:50 from ClassA is printing.
Please correct if my understanding is wrong..
Thanks in Advance

Answer 1

First, let me correct a little wording mistake:
In method overriding, at Compile time the object reference is ClassA and it looks for a method Display() in ClassA.
No, methods are not called at compile time. They are called at runtime. At runtime, the object is actually an object of ClassB, so it will look for the method in ClassB, which is why the 2 display calls bot print 25.
Okay, now you have to understand the difference between overriding and hiding. The method display is overrides so even if objA is of type ClassA, the method in ClassB is called because objA actually contains an instance of ClassB.
value, on the other hand, is hidden. When you access value, objA is a variable of type ClassA, so it looks for the value of value in ClassA, even though objA contains an object of ClassB.
If you want to override value, you have to make it a method:
class ClassA {
public int getValue() { return 50; }
public void display(){
System.out.println("ClassA displaying value:"+ getValue());
}
}
class ClassB extends ClassA {
public int getValue() { return 25; }
public void display(){
System.out.println("ClassB displaying value:"+ getValue());
}
}