EnumPractice.java

import java.util.*;

class EnumPractice{
    private enum singleton{
        INSTANCE;
        public void show(){
            System.out.println("enum show");
        }
    }

    private enum types{
        A{
            public void show(){
                System.out.println("A!!");
            }
        },
        B{
            public void show(){
                System.out.println("B!!");
            }
        };
        abstract public void show();
    }

    public static void main(String[] args){
        singleton.INSTANCE.show();
        types.A.show();
        types.B.show();

        for(final types type: types.values()){
            type.show();
        }
        return;
    }
}