switch case 穿透 示例

public class SwitchCase {
//判断输入的月份属于第几季度
    public static void main(String[] args) {
        //随机获得 1-12个月份中的一个值
        int num =(int)(Math.random()*12+1);
        //利用switch case 穿透
        switch (num){
            case 1:
            case 2:
            case 3:
                System.out.println("第一季度");
                break;
            case 4:
            case 5:
            case 6:
                System.out.println("第二季度");
                break;
            case 7:
            case 8:
            case 9:
                System.out.println("第三季度");
                break;
            case 10:
            case 11:
            case 12:
                System.out.println("第四季度");
                break;
        }

    }
}

package test;

public class Switch {
    //判断给定日期属于一年中的第几天
    public static void main(String[] args) {
        String date = "2024-12-31";
        String year = date.substring(0, 4);
        int yy = Integer.parseInt(year);
        String month = date.substring(5, 7);
        int mm = Integer.parseInt(month);
        String day = date.substring(8, 10);
        int dd = Integer.parseInt(day);
        int sum = dd;
        switch (mm) {
            case 12:
                sum += 30;
            case 11:
                sum += 31;
            case 10:
                sum += 30;
            case 9:
                sum += 31;
            case 8:
                sum += 31;
            case 7:
                sum += 30;
            case 6:
                sum += 31;
            case 5:
                sum += 30;
            case 4:
                sum += 31;
            case 3:
                if (yy % 4 == 0 && yy % 100 != 0 || yy % 400 == 0) {
                    sum += 29;
                } else {
                    sum += 28;
                }
            case 2:
                sum += 31;
            case 1:
                sum += 0;
                break;

        }
        System.out.println(date+"是"+yy+"年第"+sum+"天");
    }
}