JAVA第二周作业

import java.util.Scanner;


public class text{

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int r=2;
        double area;
        area=3.14*r*r;
        System.out.println(area);


    }

}

 

 

 

public class text2 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        double hua,she;
        hua=50;
        she=(hua-32)*5/9.0;
        System.out.println(she);
        she=30;
        hua=she*9.0/5+32;
        System.out.println(hua);

    }

}

public class text3 {
 public static void main(String[] args) {
  int a=5;
  int b=8,c;
  c=a;
  a=b;
  b=c;
  System.out.println("a:"+a+"b:"+b);
 }
}

public class text4{

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int a=12345,b;
            b=a/100*100;
            System.out.println(b);

    }

}

public class text5 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
          int a=1234,sum;
            sum=(a%10)+(a%100/10)+(a%1000/100)+(a/1000);
            System.out.println(sum);
    }

}

public class text6 {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
         char daxie,xiaoxie,shuchu;
            daxie='A';
            shuchu=(char) (daxie+32);
            System.out.println(shuchu);
            xiaoxie='a';
            shuchu=(char) (xiaoxie-32);
            System.out.println(shuchu);
    }

}