【算法】在控制台输入一个日期，判断这个日期是这一年的第几天？

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * @ClassName test
 * @Description 测试类
 * @Author asus
 * @Date 2020/12/15 16:02
 * @Version 1.0
 **/
public class Main{
    
    
    /**
     * @return
     * @Description 在控制台输入一个日期，判断这个日期是这一年的第几天？
     * @Author guojingting
     * @Date 2020/12/15 16:03
     * @Version 1.0
     * @Parm
     **/
    public static void main(String[] args) throws IOException {
    
    

        //输入这个年份的日期

        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        String date = bufferedReader.readLine();//例如：20201215   20200605
        int year = Integer.parseInt(date.substring(0, 4));
        //判断这个年份是否为闰年
        int february;//二月

        if (year % 4 == 0 || year % 100 == 0 || year % 400 == 0) {
    
    
            //如果是闰年，那么february=29,否则february=28
            february = 29;
        } else {
    
    
            february = 28;
        }

        //转换月份，如果月份中有0，那么把0去掉
        String monthStr = date.substring(4, 6);
        int month = 0;
        if (monthStr.charAt(0)=='0'){
    
    
            month = Integer.parseInt(monthStr.substring(0));
        }


        //转换day，如果day有0，那么把0去掉
        String dayStr = date.substring(6, 8);
        int day = 0;
        if (dayStr.charAt(0) == '0') {
    
    
            day = Integer.parseInt(dayStr.substring(0));
        }

        int sum=0;//总天数是多少 31 28/29 31 30 31 30 31 31 30 31 30 31
        switch (month-1){
    
    
            case 11:sum+=30;
            case 10:sum+=31;
            case 9:sum+=30;
            case 8:sum+=31;
            case 7:sum+=31;
            case 6:sum+=30;
            case 5:sum+=31;
            case 4:sum+=30;
            case 3:sum+=31;
            case 2:sum+=february;
            case 1:sum+=31;
        }

        sum+=day;
        System.out.println("年:"+year+"月："+"天"+day);

        System.out.println("天数为"+sum+"天");

    }

}