第一次java作业

1.

package test;

public class demo{

       public static void main(String[] args) {

              int a = 100;

              int b = 200;

              int tmp;

              //进行数据交换

              tmp = a;

              a = b;

              b = tmp;

              System.out.println("交换后的a:"+ a + ",b:" + b);

}

}

2.

package test;

import java.util.*;

public class demo{

       public static void main(String[] args) {

              //一个三位数整数，求各位整数的和

              System.out.println("请输入一个1~1000的整数：");

              Scanner sc = new Scanner(System.in);

              int a = sc.nextInt();

              int b, c, d, e, sum;

              e = a / 1000;

              b = a / 100 % 10;

              c = a  / 10 % 10;

              d = a % 10;

              sum = b +c +d +e;

              System.out.println("结果为" + sum);

       }

}

3.

package test;

import java.util.Scanner;

public class demo{

       public static void main(String[] args) {

              Scanner in = new Scanner(System.in);

              int fatrenheit;//输入一个华氏温度

              System.out.println("输入一个华氏度：");

              fatrenheit=in.nextInt();

              //转换为华氏温度

              int celsius =(fatrenheit-32)*5/9;

              //输出结果

              System.out.println(fatrenheit+"华氏度是"+celsius+"摄氏度");

       }

      

}

4.

package test;

import java.util.*;

public class demo{

       public static void main(String[] args) {

              System.out.println("输入一个大写字母：");

              Scanner sc = new  Scanner(System.in);

              String c = sc.next();

              char a = c.charAt(0);

              System.out.println("小写字母为"+(char)(int)(a+32));

       } 

}