Java第十次作业

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package bag;

import java.util.Arrays;

public class study {
    public static void Sort(int[]x){
        for (int i = 0; i < x.length-1; i++) {
            for (int j = 0; j < x.length-i-1; j++) {
                if (x[j]>x[j+1]) {
                    int temp = x[j];
                    x[j]=x[j+1];
                    x[j+1]=temp;
                }
            }
        }
        System.out.println(Arrays.toString(x));
    }
    public static void main(String[] args) {
        int[]y;
        y = new int[]{1,5,8,7,9,7,8,4,5};
        Sort(y);
    }
}

 

 2.编写一个方法，求整数n的阶乘，例如5的阶乘是1*2*3*4*5。 [必做题]

package bag;

public class learn {
    public static int jiecheng(int n){
        int sum = 1;
        for (int i = 1; i <= n; i++) {
            sum*=i;
        }
        return sum;
    }
    public static void main(String[] args){
        System.out.println(jiecheng(5));
    }

}

 

 3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package bag;
import java.util.Scanner;
public class learn {
    public static void nian() {
        Scanner input = new Scanner(System.in);
        System.out.println("输入年份");
        int year = input.nextInt();
        if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {
            System.out.println("闰年");
        }
        else {
            System.out.println("平年");
        }
    }

    public static void main(String[] args) {
        
        
        nian();
    }

}

 

4.输入四位会员卡号 如果百位等于随机数，就是幸运会员。询问是否返回主菜单。

 

package bag;
import java.util.Random;
import java.util.Scanner;

public class study {
    public static void mainMenu() {       
        Scanner input = new Scanner(System.in);
        System.out.println("欢迎使用本系统");
        System.out.println("1.幸运抽奖");
        System.out.println("2.退出系统");
        System.out.println(" 请选择：");
        int i = input.nextInt();
        switch (i) {
        case 1:
            register();
            break;
        }
    }
    public static void register(){
        Scanner input = new Scanner(System.in);
        System.out.println("输入四位会员卡号");
        int x=input.nextInt();
        int b=x/100%10;
        Random r = new Random();
        int ran=r.nextInt(10);        
        System.out.println("生成的随机数是"+ran);
        if (ran==b) {
            System.out.println("幸运会员");
        } else {
            System.out.println("非幸运会员");
        }
        returnMain();
    }
    public static void returnMain(){
        Scanner input = new Scanner(System.in);
        System.out.println("是否返回主菜单？Y/N");
        if(input.next().equalsIgnoreCase("Y"))
            mainMenu();
        else
            System.out.println("谢谢使用");
    }
    public static void main(String[] args) {
        mainMenu();
    }
}