第七次Java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。

package aaa;
import java.util.Arrays; 
public class aaaaa {
 
    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:a) {
            System.out.println(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。

package aaa;
 
public class aaaaa {
 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
    double a[][]= { {1,2,3,4},
            {5,6,7,8},
            {9,10,11,12},
            {13,14,15,16},
            {17,18,19,20} };
    for(int i=0;i<a.length;i++) {
        for(int j=0;j<a[i].length;j++) {
        System.out.print(a[i][j] + "");
    }
    System.out.println();
    }
    }
}

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。

package aaa;
 
public class aaaaa3 {
 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a[]= {18,25,7,36,13,2,89,63};
        int max=0,index=0;
        for(int i=0;i<a.length;i++) {
            if(a[i]>max) {
                max=a[i];
                index=i;
            }
        }
        System.out.println("最大数是"+max+"下标是"+index);
    }
 
}<br>

4、将一个数组中的元素逆序存放

package aaa;
import java.util.Scanner; 
public class aaaaa4 {
 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input=new Scanner(System.in);
        int[]a=new int[5];
        for(int i=0;i<a.length;i++) {
            a[i]=input.nextInt();
        }
        int temp;
        for(int i=0;i<a.length/2;i++) {
            temp=a[i];
            a[i]=a[a.length-1];
            a[a.length-i-1]=temp;
        }
        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。

package aaa;
import java.util.Arrays; 
public class aaaaa5 {
 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a[]= {12,32,45,36,54,56,76};
        for(int i=0;i<a.length;i++) {
            for(int j=0;j<a.length;j++) {
                if(a[i]==a[j] && i !=j)
                    a[j]=0;
            }
        }
        for(int i:a) {
            System.out.println(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。

public class test {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a[] = { -10, 2, 3, 246, -100, 0, 5 };
        int avg = 0, max = 0, min = 0;
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            sum += a[i];
            avg = sum / 7;
            if (a[i] > max) {
                max = a[i];
            }
            if (a[i] < min) {
                min = a[i];
            }
        }
        System.out.println("平均数" + avg + "最大" + max + "最小" + min);
    }
 
}

7、使用数组存放裴波那契数列的前20项，并输出

public class test {
 
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] x = new int[20];
        x[0] = 1;
        x[1] = 1;
        for (int i = 2; i < x.length; i++) {
            x[i] = x[i - 1] + x[i - 2];
        }
        for (int i = 0; i < 8; i++) {
            System.out.print(x[i] + " ");
        }
    }
 
}

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 test {
    public static void main(String[] args) {
        Random r = new Random();
        int x[] = new int[10];
        for (int i = 0; i < x.length; i++) {
            x[i] = r.nextInt(101);
        }
        for (int i = 0; i < x.length; i++) {
            System.out.print(x[i] + " ");
        }
        System.out.println("排序后：");
        Arrays.sort(x);
        for (int i = 0; i < x.length; i++) {
            System.out.print(x[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.Random;
import java.util.Scanner;
 
public class test {
    public static void mainMenu() {
        Scanner input = new Scanner(System.in);
        System.out.println("欢迎使用本系统");
        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");
        System.out.println("请选择");
        int x = input.nextInt();
        switch (x) {
        case 1:
            login();
            break;
        case 2:
            register();
            break;
        case 3:
            luckdraw();
          break;
        }
 
    }
 
    public static void luckdraw() {
      
        Scanner input = new Scanner(System.in);
        System.out.println("输入四位会员卡号");
        Random r = new Random();
        int y = r.nextInt(10);
        int num = input.nextInt();
        while (num < 1000 || num > 10000) {
            System.out.println("输入有误,重新输入");
            num = input.nextInt();
            if (num >= 1000 && num < 10000) {
                break;
            }
        }
        int b = num % 1000 / 100;
        if (b == y) {
            System.out.println("幸运会员");
        } else {
            System.out.println("不是幸运会员");
        }
 
        returnMain();
    }
 
    public static void returnMain() {
        Scanner input = new Scanner(System.in);
        System.out.println("是否返回主菜单？");
        if (input.next().equalsIgnoreCase("Y"))
            mainMenu();
        else
            System.out.println("谢谢使用");
    }
 
    public static void register() {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        System.out.println("输入要注册的用户名");
        String uname = input.next();
        System.out.println("输入注册密码");
        String pwd = input.next();
        System.out.println("注册成功");
        returnMain();
 
    }
 
    public static void login() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入用户名");
        String uname = input.next();
        System.out.println("输入密码");
        String pwd = input.next();
        if (uname.equals("admin") && pwd.equals("admin")) {
            System.out.println("成功");
        } else {
            System.out.println("失败");
        }
        returnMain();
    }
 
    public static void main(String[] args) {
        mainMenu();
    }
}