java题2

1.获取随机数：

package com.company;
public class suijishu {
    public static void main(String[] args)
    {
       int sj=(int)(Math.random()*90+10);//[0,1)->[0,90)->[10,100)。math函数得到的随机数类型为double类型。公式：[a,b]: (int)(Math.rendom()*(b-a+1)+a);
        System.out.println(sj);
    }
}
2.及格问题：（60分以上及格）
package com.company;
public class SwitchCaseTest1 {
    public static void main(String[] args)
    {
        int score=78;
      switch (score/10)
       {
           case 0:
           case 1:
           case 2:
           case 3:
           case 4:
           case 5:
               System.out.println("不及格");
              break;
           case 6:
           case 7:
           case 8:
           case 9:
           case 10:
               System.out.println("及格");
               break;
       }

      switch(score/60)
       {
           case 0:
               System.out.println("不及格");
               break;
          case 1:
              System.out.println("及格");
              break;
        }


    }
}
3.输入年月日求具体是当年的第几天：
package com.company;
import java.util.Scanner;
public class SwitchCaseTest2
{
    public static void main(String[] args)
    {
        Scanner scan=new Scanner(System.in);
        System.out.println("请输入年月份：");
        int year=scan.nextInt();
        System.out.println("请输入"+year +"年月份：");
        int month=scan.nextInt();
        System.out.println("请输入"+year+"年"+month+"月的第几天：");
        int day=scan.nextInt();
        int sumDays=0;

        switch(month)
        {
            case 12:
                 sumDays+=30;
            case 11:
                  sumDays+=31;
            case 10:
                sumDays+=30;
            case 9:
                sumDays+=31;
            case 8:
                sumDays+=31;
            case 7:
                sumDays+=30;
            case 6:
                sumDays+=31;
            case 5:
                sumDays+=30;
            case 4:
                sumDays+=31;
            case 3://闰年：可以被4整除且不能被100整除，或者可以被400整除。
                if ((year%4==0&&year%100!=0)||year%400==0) {
                    sumDays+=29;
                }
                else
                     sumDays+=28;
            case 2:
                sumDays+=31;
            case 1:
                sumDays+=day;
        }
        System.out.println("这是第"+year+"年的第"+sumDays+"天");
    }
}
4.1到100奇数，并求奇数和

package com.company;

public class ForTest1 {
    public static void main(String[] args)
    {
        int sum=0;
    for (int i=1;i<=100;i++)
        {
            if (i%2!=0)
            {
                System.out.println(i);
               sum+=i;
            }
        }
        System.out.println(sum);
    }
}