Java Enum用法总结

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常量

枚举类可以用来当做常量使用，非常的方便。

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public enum Color {
    RED, GREEN, BLACK, YELLOW
}

枚举类可以做switch中的判定类型

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public class Aweek {
    Day day = Day.MONDAY;
    public void getDay() {
        switch (day) {
            case MONDAY:
                day = Day.MONDAY;
                break;
            case TUESDAY:
                day = Day.TUESDAY;
                break;
            case WEDSDAY:
                day = Day.WEDSDAY;
                break;
            case THURSDAY:
                day = Day.THURSDAY;
                break;
            case SATURDAY:
                day = Day.SATURDAY;
                break;
            case SUNDAY:
                day = Day.SUNDAY;
                break;
            case FRIDAY:
                day = Day.FRIDAY;
                break;
        }
        System.out.println(day);
    }
    public static void main(String[] args) {
        new Aweek().getDay();
    }
}
enum Day {
    MONDAY, TUESDAY, WEDSDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY
}

枚举中可以添加方法，也可以覆盖方法

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public enum Colors{
    RED("red", 1), GREEN("green", 2), BLANK("blank", 3), YELLOW("yellow", 4);
    //成员变量
    private String name;
    private int index;
    // 构造方法
    Colors(String name, int index) {
        this.name = name;
        this.index = index;
    }
    // 覆盖方法
    @Override
    public String toString() {
        return this.index + "" + this.name;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getIndex() {
        return index;
    }
    public void setIndex(int index) {
        this.index = index;
    }
    //普通方法
    public static String getName(int index) {
        for (Colors colors : Colors.values()) {
            if (colors.getIndex() == index)
                return colors.getName();
        }
        return null;
    }
}

枚举类可以实现接口，但是不能继承类

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public interface Print {
    void print();
}
public enum Colors implements Print{
    RED("red", 1), GREEN("green", 2), BLANK("blank", 3), YELLOW("yellow", 4);
    //成员变量
    private String name;
    private int index;
    // 构造方法
    Colors(String name, int index) {
        this.name = name;
        this.index = index;
    }
    @Override
    public void print() {
        System.out.println("haha");
    }
}

使用接口来组织枚举的结构

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