自定义实现和JDK提供的三种类型的枚举

第一种：
自定义

public class Direction {
    // 创建几个实例

    public static final Direction FRONT = new Direction();
    public static final Direction BEHIND = new Direction();
    public static final Direction LEFT = new Direction();
    public static final Direction RIGHT = new Direction();

    // 构造私有，别人就不能无限的创建了

    private Direction() {
    }
}

JDK

/*
 * 通过JDK5提供的枚举来做枚举类
 */
public enum Direction {
    FRONT, BEHIND, LEFT, RIGHT;
}

第二种

public class Direction2 {
    // 创建几个实例

    public static final Direction2 FRONT = new Direction2("前");
    public static final Direction2 BEHIND = new Direction2("后");
    public static final Direction2 LEFT = new Direction2("左");
    public static final Direction2 RIGHT = new Direction2("右");

    // 构造私有，别人就不能无限的创建了

    // private Direction2() {

    // }


    // 加入成员变量,并去掉无参构造

    private String name;

    private Direction2(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

/*
 * 通过JDK5提供的枚举来做枚举类
 */
public enum Direction2 {
    FRONT("前"), BEHIND("后"), LEFT("左"), RIGHT("右");

    private String name;

    private Direction2(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }


}

第三种

public abstract class Direction3 {
    // 创建几个实例

    public static final Direction3 FRONT = new Direction3("前") {
        @Override
        public void show() {
            System.out.println("前");
        }

    };
    public static final Direction3 BEHIND = new Direction3("后") {
        @Override
        public void show() {
            System.out.println("后");
        }

    };
    public static final Direction3 LEFT = new Direction3("左") {
        @Override
        public void show() {
            System.out.println("左");
        }

    };
    public static final Direction3 RIGHT = new Direction3("右") {
        @Override
        public void show() {
            System.out.println("右");
        }

    };

    // 构造私有，别人就不能无限的创建了

    // private Direction2() {

    // }


    // 加入成员变量,并去掉无参构造

    private String name;

    private Direction3(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    // 加入抽象方法

    public abstract void show();
}

/*
 * 通过JDK5提供的枚举来做枚举类
 */
public enum Direction3 {
    FRONT("前") {
        @Override
        public void show() {
            System.out.println("前");
        }
    },
    BEHIND("后") {
        @Override
        public void show() {
            System.out.println("后");
        }
    },
    LEFT("左") {
        @Override
        public void show() {
            System.out.println("左");
        }
    },
    RIGHT("右") {
        @Override
        public void show() {
            System.out.println("右");
        }
    };

    private String name;

    private Direction3(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public abstract void show();
}