第一次实训作业

1、判断奇偶数

package javaApplication;
import java.util.*;
public class Odevity
{
    public static void main(String[] args)
    {
        Scanner scanner=new Scanner(System.in);
        int x;
        System.out.println("请输入一个数：");
        x=scanner.nextInt();
        if(x%2==0)
        {
            System.out.println("这个数是偶数");
        }
        else
        {
            System.out.println("这个数是奇数");
        }
        scanner.close();
    }   
}

 

2、求圆面积

package javaApplication;
import java.util.*;
public class Circle1
{
    final static double PI=3.14159;
    public static void main(String[] args)
    {
        Scanner scanner=new Scanner(System.in);
        int r;
        double s=0;
        System.out.println("请输入半径：");
        r=scanner.nextInt();
       
        s=PI*r*r;
        System.out.printf("面积为：%.2f",s);
        scanner.close();   
    }
}

 

3、加密数字

package javaApplication;
import java.util.Scanner;
public class Encipher
{
    public static void main(String[] args)
    {
        Scanner scanner=new  Scanner(System.in);
        System.out.println("请输入要加密的数：");
        int x=scanner.nextInt();
        int y=(int)((x*10+5)/2+3.14159);
        System.out.println("加密后为："+y);
        scanner.close();
    }
}

 

 

4、不同且不重复的三位数

package javaApplication;

public class ThreeDigitNumber
{
    public static void main(String[] args)
    {
       
        int n=0;
        for(int i=1;i<=4;i++) //i表示百位
        {
            for(int j=1;j<=4;j++) //j表示十位
            {
                if(i==j)
                {
                    continue;
                }
                for(int l=1;l<=4;l++) //l表示各个位
                {
                    if(l==j||l==i)
                    {
                        continue;
                    }
                    n++;
                    System.out.print((i*100+j*10+l)+" ");
                    if(n%6==0)
                    {
                        System.out.println();
                    }   
                }
            }
        }
        System.out.println("共有"+n+"个不同的三位数。");   
    }

}

 

5、求素数

package javaApplication;
import java.util.Scanner;
public class Prime
{
    public static void main(String args[])
    {
        Scanner scanner=new Scanner(System.in);
        System.out.println("请输入一个数：");
        int x=scanner.nextInt();
        for(int i=2;i<x;i++)
        {
           
            if(x%i==0)
            {
                System.out.println("该数不是素数！");
                scanner.close();
                return ;
            }
        }   
        System.out.println("该数是素数！");   
        scanner.close();       
    }   
}