calling method on enum

Question

public enum AgeGroup {
        CHILD{
           public int get(){
               return 10;
           } 
        }, 
        TEEN, YOUNG, MID, OLD;
    }

I have an enum AgeGroup and as you are seeing that CHILD has one method get(). Can somebody tell me why we can't call get() from CHILD what is the design approach behind this or why is it designed like this?

Answer 1

Firstly, all instances of an enum are of the same type, which means all instances have the same set of methods.

You need to declare a method on the enum type itself for instances to have a method:

public enum AgeGroup {
    CHILD{
       public int get(){
           return 10;
       } 
    }, 
    TEEN, YOUNG, MID, OLD;
    public int get() {
        return 0;
    }
}

If all instances overrode the get() method as CHILD has, you could declare the method as abstract, which forces the coder to implement the method if new instances are added.

The best approach is to use a final field, initialized via a custom constructor, with a getter:

public enum AgeGroup {
    CHILD{10), TEEN(19), YOUNG(35), MID(50), OLD(80);
    private final int age;
    AgeGroup(int age) {
        this.age = age;
    }
    public int get() {
        return 
    }
}