Java枚举类
1.枚举类入门
Java枚举类是从Java5开始支持的。
枚举类的构造方法是用private修饰的。枚举类的所有实例必须在类的第一行列出，否则这个枚举类不会产生对象。
而且这些实例都是public static void.
每个枚举类都有一个values方法，该方法可以遍历枚举类的所有实例
public class Test {
public static void tell(Season s)
{
switch(s)
{
case Spring:
System.out.println(s+"春天");
break;
case Summer:System.out.println(s+"夏天");
break;
case Fall:System.out.println(s+"秋天");
break;
case Winter:System.out.println(s+"冬天");
break;
}
}
public static void main(String[] args) {
for(Season s:Season.values())
{
System.out.println(s);
}
tell(Season.Fall);
}
}
enum Season
{
Spring,Summer,Fall,Winter;
}
2.枚举类的构造方法和对象
枚举类的构造方法是private，所以不能使用new创建对象
可以使用Enum.valueOf(Class c,String s);创建对象
public class Test {
public static void main(String[] args) {
Season s=Enum.valueOf(Season.class, "Summer");
System.out.println(s);
}
}
enum Season
{
Spring,Summer,Fall,Winter;
}
一旦为枚举类定义了带参数的构造方法后，列举枚举类就必须对应的传入参数
public class Test {
public static void main(String[] args) {
Season s=Enum.valueOf(Season.class, "Summer");
System.out.println(s.name);
}
}
enum Season
{
Spring("春天"),Summer("夏天"),Fall("秋天"),Winter("冬天");
public String name;
private Season(String name)
{
this.name=name;
}
}
3.枚举类实现接口
与普通类一样，枚举类实现接口，则必须实现接口中所有的方法
public class Test {
public static void main(String[] args) {
Season s=Enum.valueOf(Season.class, "Summer");
System.out.println(s.name);
s.printInfo();
}
}
enum Season implements Infomation
{
Spring("春天"),Summer("夏天"),Fall("秋天"),Winter("冬天");
public String name;
private Season(String name)
{
this.name=name;
}
@Override
public void printInfo() {
System.out.println(name);
}
}
interface Infomation
{
void printInfo();
}
也可以使用匿名内部类的方法为每一个枚举类对象实现接口
public class Test {
public static void main(String[] args) {
Season s=Enum.valueOf(Season.class, "Summer");
System.out.println(s.name);
s.printInfo();
}
}
enum Season implements Infomation
{
Spring("春天"){
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("春天温暖");
}
},Summer("夏天")
{
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("夏天炎热");
}
},Fall("秋天")
{
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("秋天凉爽");
}
},Winter("冬天"){
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("冬天寒冷");
}
};
public String name;
private Season(String name)
{
this.name=name;
}
}
interface Infomation
{
void printInfo();
}
4.包含抽象方法的枚举类
包含抽象方法枚举类，要实例化对象的话，就得让每个对象实现抽象方法
public class Test {
public static void main(String[] args) {
Season s=Enum.valueOf(Season.class, "Summer");
System.out.println(s.name);
s.printInfo();
s.whatToDo();
}
}
enum Season implements Infomation
{
Spring("春天"){
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("春天温暖");
}
@Override
public void whatToDo() {
// TODO Auto-generated method stub
System.out.println("我去春游");
}
},Summer("夏天")
{
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("夏天炎热");
}
@Override
public void whatToDo() {
// TODO Auto-generated method stub
System.out.println("我去游泳");
}
},Fall("秋天")
{
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("秋天凉爽");
}
@Override
public void whatToDo() {
// TODO Auto-generated method stub
System.out.println("我去玩乒乓球");
}
},Winter("冬天"){
@Override
public void printInfo() {
// TODO Auto-generated method stub
System.out.println("冬天寒冷");
}
@Override
public void whatToDo() {
// TODO Auto-generated method stub
System.out.println("我去赏雪观梅");
}
};
public String name;
private Season(String name)
{
this.name=name;
}
public abstract void whatToDo();
}
interface Infomation
{
void printInfo();
}