Java 枚举(enum) 常见的用法
用法一：常量 在JDK1.5 之前，我们定义常量都是： public static fianl.... 。现在好了，有了枚举，可以把相关的常量分组到一个枚举类型里，而且枚举提供了比常量更多的方法 public enum Color { RED, GREEN, BLANK, YELLOW }
用法二：switch JDK1.6之前的switch语句只支持int,char,enum类型，使用枚举，能让我们的代码可读性更强
enum Signal { GREEN, YELLOW, RED } public class TrafficLight { Signal color = Signal.RED; public void change() { switch (color) { case RED: color = Signal.GREEN; break; case YELLOW: color = Signal.RED; break; case GREEN: color = Signal.YELLOW; break; } } } 用法三：向枚举中添加新方法 如果打算自定义自己的方法，那么必须在enum实例序列的最后添加一个分号。而且 Java 要求必须先定义 enum 实例
public enum Color { RED("红色", 1), GREEN("绿色", 2), BLANK("白色", 3), YELLO("黄色", 4); private String name; private int index; private Color(String name, int index) { this.name = name; this.index = index; } public static String getName(int index) { for (Color c : Color.values()) { if (c.getIndex() == index) { return c.name; } } return null; } 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; } }
用法四：覆盖枚举的方法 下面给出一个toString()方法覆盖的例子
public enum Color { RED("红色", 1), GREEN("绿色", 2), BLANK("白色", 3), YELLO("黄色", 4); private String name; private int index; private Color(String name, int index) { this.name = name; this.index = index; } @Override public String toString() { return this.index+"_"+this.name; } } 用法五：实现接口 所有的枚举都继承自java.lang.Enum类。由于Java 不支持多继承，所以枚举对象不能再继承其他类。
public interface Behaviour { void print(); String getInfo(); } public enum Color implements Behaviour{ RED("红色", 1), GREEN("绿色", 2), BLANK("白色", 3), YELLO("黄色", 4); private String name; private int index; private Color(String name, int index) { this.name = name; this.index = index; } @Override public String getInfo() { return this.name; } @Override public void print() { System.out.println(this.index+":"+this.name); } }
用法六：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 } } private static void testImplementsInterface() { for (Food.DessertEnum dessertEnum : Food.DessertEnum.values()) { System.out.print(dessertEnum + " "); } System.out.println(); for (CoffeeEnum coffee : CoffeeEnum.values()) { System.out.print(coffee + " "); } System.out.println(); Food food = Food.DessertEnum.CAKE; System.out.println(food); food = CoffeeEnum.BLACK_COFFEE; System.out.println(food); }
| 
收藏
淘帖
踩
