switch语句是一种高效的多路语句，可以省掉很多繁杂的嵌套if判断；
在Java 6及之前，case语句中的常量只能是byte、char、short和int（也可以是对应的封装类）或枚举常量，在Java 7规范中增加了String，毕竟它也是常量类型；
Demo：
public class CoinSwitchString {
public static void main(String[] args) {
printDay("Sunday");
printDay("Tuesday");
printDay("Ten");
}
public static void printDay(String dayOfWeek) {
switch(dayOfWeek) {
case "Sunday": System.out.println("星期日"); break;
case "Monday": System.out.println("星期一"); break;
case "Tuesday": System.out.println("星期二"); break;
case "Wednesday": System.out.println("星期三"); break;
case "Thursday": System.out.println("星期四"); break;
case "Friday": System.out.println("星期五"); break;
case "Saturday": System.out.println("星期六"); break;
default: System.out.println("Error: '" + dayOfWeek + "' is not a day of the week!");
}
}
}
Ran As Java Application：
星期日
星期二
Error: 'Ten' is not a day of the week!