Question

public class CovariantTest {     public A getObj() {         return new A();     }      public static void main(String[] args) {         CovariantTest c = new SubCovariantTest();         System.out.println(c.getObj().x);     } }  class SubCovariantTest extends CovariantTest {     public B getObj() {         return new B();     } }  class A {     int x = 5; }  class B extends A {     int x = 6; } 

The above code prints 5 when compiled and run. It uses the covariant return for the over-ridden method.

Why does it prints 5 instead of 6, as it executes the over ridden method getObj in class SubCovariantTest.

Can some one throw some light on this. Thanks.

Answer 1

This is because in Java member variables don’t override, they shadow (unlike methods). Both A and B have a variable x. Since c is declared to be of type CovarientTest, the return of getObj() is implicitly an A, not B, so you get A’s x, not B’s x.