package com.karl; //if在功能上远远强大于switch //当前条件是区间的时候,应该使用if分支结构 //switch适合做:条件是比较值的情况,代码优雅,性能较好 public class SwitchDemo { public static void main(String[] args) { String week="周六"; switch (week){ case "周一": System.out.println("吃"); break; case "周二": System.out.println("喝"); break; case "周三": System.out.println("玩"); break; case "周四": System.out.println("乐"); break; case "周五": System.out.println("睡"); break; case "周六": System.out.println("打"); break; case "周天": System.out.println("ak"); break; default: System.out.println("输入日期错误"); } System.out.println("________________________________________________"); //1.表达式类型只能是byte.shout.int.char // JDK5开始支持Strig,不支持double.float.long. int a=10; double b=0.1; long c=5; switch (a){ } //case给出的值不允许重复,不能是变量 //正常使用switch的时候,不要忘记break,否则会出现穿透现象(没有break就不会停止会继续打印) String day="5"; switch (day){ case "1": case "2": case "3": System.out.println("dayouxi"); break; case "4": System.out.println("shuijiao"); break; case "5": case "6": case "7": System.out.println("lllllll"); break; default: System.out.println("cuowu"); } } }