2020.3.20.第二次java作业

1.输入一个年份,判断是不是闰年(能被4整除但不能被100整除,或者能被400整除)

package com.itheima01;
import java.util.Scanner;
public class HelloWorld {
     public static void main(String[] args) {
         System.out.println("请输入年份");
         Scanner input=new Scanner(System.in);   
         int a = input.nextInt();
         if(a%4==0&&a%4!=0) {
             System.out.println("是闰年");
          }else if(a%400==0) {
           System.out.println("是闰年");
          }else {
          System.out.println("不是闰年");
         }
         }
}

 2.输入一个4位会员卡号,如果百位数字是3的倍数,就输出是幸运会员,否则就输出不是

package com.itheima01;
import java.util.Scanner;
public class HelloWorld {
     public static void main(String[] args) {
          System.out.println("输入四位会员卡号");
          Scanner input=new Scanner(System.in);
          int a = input.nextInt();
          if(a/100%10%3==0) {
           System.out.println("是幸运会员");
          }else System.out.println("不是幸运会员");
         }
}

 3.已知函数,输入x的值,输出对应的y的值.
        x + 3 ( x > 0 )
y =  0 ( x = 0 )
        x*2 –1 ( x < 0 )

package com.itheima01;
import java.util.Scanner;
public class HelloWorld {
    public static void main(String[] args) {
         System.out.println("请输入x的值，此程序输出对应y值");
          Scanner input = new Scanner(System.in);
          double x=input.nextDouble();
          double y;
          if(x>0) {
           y=x+3;
           System.out.println("对应的y值为"+y);
          }else if(x==0) {
           y=x;
           System.out.println("对应的y值为"+y);
          }else if(x<0) {
           y=2*x-1;
           System.out.println("对应的y值为"+y);
          }
           
        }
}

 4.输入三个数,判断能否构成三角形(任意两边之和大于第三边)

package com.itheima01;
import java.util.Scanner;
public class HelloWorld {
    public static void main(String[] args) {
         System.out.println("请输入三个数，判断能否构成三角形");
          Scanner input = new Scanner(System.in);
          double a=input.nextDouble();
          double b=input.nextDouble();
          double c=input.nextDouble();
          if(a+b>c) {
           if(a+c>b) {
            if(b+c>a) {
             System.out.println("可以构成三角形");
            }
           }
           else {
            System.out.println("不能构成三角形");
           }
          }else {
           System.out.println("不能构成三角形");
          }           
        }
}