java第9次作业

1、给定一个有9个整数（1,6,2,3,9,4,5,7,8）的数组，先排序，然后输出排序后的数组的值

import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int a[]= {1,6,2,3,9,4,5,7,8};        
            Arrays.sort(a);
            for (int i = 0; i < a.length; i++) {
                System.out.println(a[i]);
            }
    }

}

  2、 输出一个double型二维数组（长度分别为5、4，值自己设定）的值

import java.util.Scanner;
import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        double a[][]=new double[4][5];    
        Scanner input=new Scanner(System.in);
        System.out.println("输入数");
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 5; j++) {
                a[i][j]=input.nextDouble();
            }
        }
        for(int i = 0; i < 4; i++) {
            for (int j = 0; j < 5; j++) {
                System.out.print(a[i][j]+" ");
            }
            System.out.print("\n");
        }
    }

}

 3、 在一个有8个整数（18，25，7，36，13，2，89，63）的数组中找出其中最大的数及其下标。

import java.util.Scanner;
import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int a[]={18,25,7,36,13,2,89,63};    
            Arrays.sort(a);
            System.out.println("最大值是"+a[a.length-1]+"下表是"+a.length);
    }

}

 4、将一个数组中的元素逆序存放

import java.util.Scanner;
import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a[]={18,25,7,36,13,2,89,63};    
        for (int i = 0; i < a.length; i++) {
        for (int j = 1; j < a.length; j++) {
            int l=0;
            if (a[j-1]<a[j]) {
                l=a[j-1];
                a[j-1]=a[j];
                a[j]=l;
            }
        }    
        }
        for (int i = 0; i < a.length; i++) {
            System.out.println(a[i]);
        }
    }

}

 5. 将一个数组中的重复元素保留一个其他的清零。

import java.util.Scanner;
import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int a[]= {4,5,8,5,6,6,4,9,9};
            for (int i = 0; i < a.length; i++) {
            for (int j = 1; j < a.length; j++) {
                int l=0;
                if (a[j-1]<a[j]) {
                    l=a[j-1];
                    a[j-1]=a[j];
                    a[j]=l;
                }
            }
            }
            for (int i = 0; i < a.length; i++) {
                for (int j = 1; j < a.length; j++) {
                    int l=0;
                    if (a[j-1]==a[j]) {
                        a[j]=l;
                    }
                }
                }
            for (int i = 0; i < a.length; i++) {
                System.out.println(a[i]);
            }
    }

}

 6、给定一维数组{ -10，2，3，246，-100，0，5}，计算出数组中的平均值、最大值、最小值

import java.util.Arrays;
public class asdjk {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
         int a[]= {-10,2,3,246,-100,0,5,};
         int sum=0,k;
         Arrays.sort(a);
         for (int i = 0; i < a.length; i++) {
             sum+=a[i];
         }
         k=sum/a.length;
         System.out.println("最小值"+a[a.length-1]);
         System.out.println("最大值"+a[0]);
         System.out.println("平均值"+k);
    }

}

  7、使用数组存放裴波那契数列的前20项 ，并输出

import java.util.Scanner;

public class asdjk {

    public static int fu(int n){
        // TODO Auto-generated method stub
         int a=1;
            int b=1;
            int c=0;
            if(n==1||n==2) {
                return 1;
            }else {
                for (int i = 3; i <= n; i++) {
                    c=a+b;
                    a=b;
                    b=c;
                }
                return c;
            }        
        }
        public static void main(String[] args) {
            var Scanner=new Scanner(System.in);
            int a[]=new int[100];        
            for (int i = 1; i < 21; i++) {    
                int n=i;
                a[i-1]=fu(n);
                
                
            }
            for (int j = 0; j < 20; j++) {
                System.out.println(a[j]);
            }
    }

}

8、生成一个长度为10的随机整数数组（每个数都是0-100之间），输出，排序后，再输出

import java.util.Arrays;
import java.util.Random;

public class asdjk {

     public static void main(String[] args) {
            Random rand=new Random();
            int a[]=new int[10];
            
            for (int i = 0; i <10; i++) {
                a[i]=rand.nextInt(100);
            }
            Arrays.sort(a);
            for (int i = 0; i < a.length; i++) {
                System.out.print(a[i]+" ");
            }
    }

}

 9、做一个菜单切换程序。主菜单1.登陆 2.注册 3幸运抽奖 4 退出。每个菜单可以返回主菜单

import java.util.Arrays;
import java.util.Random;
import java.util.Scanner;

public class asdjk {

    public static void zhuce() {
        var scanner=new Scanner(System.in);
        System.out.println("输入用户名");            
        String name = scanner.next();
        System.out.println("输入密码");
        String pwd = scanner.next();
        System.out.println("确认密码");
        String pwd1 = scanner.next();
        System.out.println("是否返回登录？y/n");
        if (scanner.next().equalsIgnoreCase("y")) {
            caidanmain();            
        }
            
}


    public static void denglu(){
        var scanner=new Scanner(System.in);
        System.out.println("请输入用户名");
        String name=scanner.next();
        System.out.println("请输入密码");
        String mm=scanner.next();
        if (name.equals(mm)) {
            System.out.println("登陆成功");
        }else {
            System.out.println("登录失败");
        }
        caidanmain();
}

    public static void choujiang() {
        Random r=new Random();
        var scanner=new Scanner(System.in); 
        int rand=r.nextInt(100);
        System.out.println("输入一个数");
        int a=scanner.nextInt();
        if(rand==a) {
        System.out.println("中奖了");
         }else {
            System.out.println("没中奖");
         }
           System.out.println(rand);
           System.out.println("是否返回登录？y/n");
           if (scanner.next().equalsIgnoreCase("y")) {
               caidanmain();            
           }
        
}
    
    public static void caidanmain() {
        var scanner=new Scanner(System.in);
        System.out.println("1:登录");
        System.out.println("2:注册");
        System.out.println("3:幸运抽奖");
        System.out.println("4:退出");
        int i=scanner.nextInt();
        switch (i) {
        case 1:
            denglu();
            break;
        case 2:
            zhuce();
            break;
        case 3:
            choujiang();
            break;
        case 4:
            break;
        }
    }
    
    public static void main(String[] args) {
        caidanmain();
    }

}