JavaSE8基础 switch 两个case执行同样的语句

package jizuiku0;

import java.util.Scanner;

/*
* @version V17.09
*/
public class Demo_001 {
public static void main(String[] args) {

Scanner sc = new Scanner(System.in);
int key = sc.nextInt();
sc.close();
// IDE的格式是这样的
switch (key) {
case 1:
System.out.println("key是1");
break;
case 2:
System.out.println("key是2");
break;
case 3:
case 4:
System.out.println("hello world");
break;
// 补上default是个好习惯
default:
break;
}
}
}