１ 定义一个枚举
enum Weekend {
Monday,
Tuesday,
Wednesday,
Thursday,
Friday,
Saturday,
Sunday
}
２ 得到每个枚举值
for (Weekend weekend : Weekend.values())
３ 返回枚举在集合中顺序（从０开始）
public final int ordinal() {
return ordinal;
}
４ 当前枚举名字
public final String name() {
return name;
}
５ 根据名字返回相应的enum实例
public static <T extends Enum<T>> T valueOf(Class<T> enumType,
String name) {
T result = enumType.enumConstantDirectory().get(name);
if (result != null)
return result;
if (name == null)
throw new NullPointerException("Name is null");
throw new IllegalArgumentException(
"No enum constant " + enumType.getCanonicalName() + "." + name);
}
6 枚举不能被继承（下面的代码报错，提示不能从final的test.Weekday继承）
enum WeekendSon extends Weekend {
}
7 定义enum构造函数
enum Step { // Instances must be defined first, before methods:
First("this is the first step"),
Second("this is the second step"),
Third("this is the third step"),
Fourth("this is the fourth step");
private String description;
public String getDescription() {
return description;
}
Step(String description) {
this.description = description;
}
}
public class AppTest {
public static void main(String[] args) {
for (Step step : Step.values()) {
System.out.println(step + ":" + step.getDescription());
}
}
}
输出结果：
First:this is the first step Second:this is the second step Third:this is the third step Fourth:this is the fourth step
8 实例一枚
State接口:
public interface State {
int getCode();
String getDesc();
State nameOf(String var1);
}
LifeState枚举:
public enum LifeState implements State {
babyState(0, "儿童状态"),
youngState(1, "年轻状态"),
adultState(2, "成年状态"),
oldState(3, "老年状态");
private int code;
private String desc;
private LifeState(int code, String desc) {
this.code = code;
this.desc = desc;
}
@Override
public int getCode() {
return this.code;
}
@Override
public String getDesc() {
return this.desc;
}
@Override
public State nameOf(String name) {
return valueOf(name);
}
public static LifeState codeOf(int code) {
LifeState[] arr = values();
for(int i = 0; i < arr.length; i++) {
if(arr[i].code == code) {
return arr[i];
}
}
return null;
}
}
Test测试类:
public class Test {
public static void main(String[] args) {
LifeState lifeState = LifeState.babyState;
System.out.println(lifeState + "---" + lifeState.getCode() + "---" + lifeState.getDesc());
State babyState = lifeState.nameOf("youngState"); //调用valueOf,返回相应的枚举实例
System.out.println(babyState + "---" + babyState.getCode() + "---" + babyState.getDesc());
System.out.println(LifeState.codeOf(3).getDesc());
System.out.println(LifeState.youngState.name());
}
}
运行结果：
babyState---0---儿童状态 youngState---1---年轻状态 老年状态 youngState