Java中关于枚举的7种用法

1.定义常量：

public enum Color {
    RED,ORANGE,YELLOW,GREEN,INDIGO,BLUE,PURPLE
}

2.用于switch：

enum Color {
    RED,ORANGE,YELLOW,GREEN,INDIGO,BLUE,PURPLE
}
public class Draw{
    Color c = Color.BLUE;
    public void draw(){
        switch(c){
        case RED:
            c = Color.RED;
            break;
        case ORANGE:
            c = Color.ORANGE;
            break;
        case YELLOW:
            c = Color.YELLOW;
            break;
        case GREEN:
            c = Color.GREEN;
            break;
        case INDIGO:
            c = Color.INDIGO;
            break;
        case BLUE:
            c = Color.BLUE;
            break;
        case PURPLE:
            c = Color.PURPLE;
            break;
        }
    }
} 

3.在枚举中添加新方法：

public enum Color {
    RED(1,"红"),
    ORANGE(2,"橙"),
    YELLOW(3,"黄"),
    GREEN(4,"绿"),
    INDIGO(5,"靛"),
    BLUE(6,"蓝"),
    PURPLE(7,"紫");
    //成员变量
    private int sequence;
    private String name;
    //构造方法
    private Color(int sequence, String name) {
        this.sequence = sequence;
        this.name = name;
    }
    //自定义方法
    public static String getColorName(int sequence){
        for (Color c : Color.values()) {
            if(c.getSequence() == sequence)
                return c.name;
        }
        return null;
    }
    //getter&setter
    public int getSequence() {
        return sequence;
    }
    public void setSequence(int sequence) {
        this.sequence = sequence;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

4.覆盖（重写）枚举的方法：

public enum Color {
    RED(1,"红"),
    ORANGE(2,"橙"),
    YELLOW(3,"黄"),
    GREEN(4,"绿"),
    INDIGO(5,"靛"),
    BLUE(6,"蓝"),
    PURPLE(7,"紫");
    //成员变量
    private int sequence;
    private String name;
    //构造方法
    private Color(int sequence, String name) {
        this.sequence = sequence;
        this.name = name;
    }
    //覆盖方法
    @Override
    public String toString() {
        return "顺序："+this.sequence+"_颜色名："+this.name;
    }
}

5.实现接口：

interface Action{
    void getDetail();
}
public enum Color implements Action{
    RED(1,"红"),
    ORANGE(2,"橙"),
    YELLOW(3,"黄"),
    GREEN(4,"绿"),
    INDIGO(5,"靛"),
    BLUE(6,"蓝"),
    PURPLE(7,"紫");
    //成员变量
    private int sequence;
    private String name;
    //构造方法
    private Color(int sequence, String name) {
        this.sequence = sequence;
        this.name = name;
    }
    @Override
    public void getDetail() {
        System.out.println("顺序："+this.sequence+"_颜色名："+this.name);
    }
}

6.使用接口组织枚举：

public interface Food {
    enum Coffee implements Food{
        BLACK_COFFEE,DECAF_COFFEE,LATTE,CAPPUCCINO
    }
    enum Dessert implements Food{
        FRUIT, CAKE, GELATO
    }
}  

7.枚举集合：

java.util.EnumSet和java.util.EnumMap是两个枚举集合。EnumSet保证集合中的元素不重复；EnumMap中的key是enum类型，而value则可以是任意类型。