# 003public class Switch-case結構式 {
switch (n) {case 1:敘述1;break;
case 2:敘述2;break;
default:敘述4;}
亂數月份/當月天數判斷
```
public static void main(String[] args) {
int Month = (int)(Math.random()*12 + 1); // 1 - 12
System.out.println(Month);
switch (Month){
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
System.out.println("31");
break;
case 4: case 6: case 9: case 11:
System.out.println("30");
break;
case 2:
System.out.println("28");
break;
default:(其他)
System.out.println("OK");
}
}
}
```