Overriding Constants in Java

Question

I have two classes that extend the same abstract class. They both need the same constant, but with different values. How can I do this? Some example code to show what I want to do.

abstract class A {    public static int CONST; }  public class B extends A {    public static int CONST = 1; }  public class C extends A {    public static int CONST = 2; }  public static void main(String[] args){     A a = new B();     System.out.println(a.CONST); // should print 1 } 

The above code does not compile because CONST is not initialized int class A. How can I make it work? The value of CONST should be 1 for all instances of B, and 2 for all instances of C, and 1 or 2 for all instances of A. Is there any way to use statics for this?

Answer 1

You can't do that.

You can do this, however:

abstract class A {    public abstract int getConst(); }  public class B extends A {    @Override    public int getConst() { return 1; } }  public class C extends A {    @Override    public int getConst() { return 2; } }  public static void main(String[] args){     A a = new B();     System.out.println(a.getConst()); } 

Answer 2

If a constant has a variable value, it's not a constant anymore. Static fields and methods are not polymorphic. You need to use a public method to do what you want.