# Java第九次作业

1.编写一个方法，实现冒泡排序（由小到大），并调用该方法

package work;

public class test {
public static void main(String[] args) {
int[] a = { 3, 9, 5, 45, 67, 99, 56 };
test.mp(a);

}

public static void mp(int a[]) {
for (int i = 1; i < a.length; i++) {
for (int j = 0; j < a.length - i; j++) {
if (a[j] > a[j + 1]) {
int temp = a[j];
a[j] = a[j + 1];
a[j + 1] = temp;
}
}
}
for (int b : a) {
System.out.print(b + " ");
}
}
}

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 work;

import java.util.Scanner;

public class test {
public static void main(String[] args) {
jc();
}
public static void jc() {
Scanner input = new Scanner(System.in);
System.out.println("请输入整数：");
int a = input.nextInt();
int jie=1;
for (int i = 1;  i<=a; i++) {
jie*=i;

}
System.out.println(jie);
}
}

3.编写一个方法，判断该年份是平年还是闰年。[必做题]

package work;

import java.util.Scanner;

public class test {
public static void main(String[] args) {
yp();
}

public static void yp() {
Scanner input = new Scanner(System.in);
System.out.println("请输入年份");
int year = input.nextInt();
if (year % 4 == 0 && year % 100 != 100 || year % 400 == 0) {
System.out.println("该年份为闰年");
} else {
System.out.println("该年份为平年");
}
}
}

package work;

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

public class test {
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 i=input.nextInt();
switch(i){
case 1:
break;
case 2:
reg();
break;
case 3:
lucky();

}

}

private static void lucky() {
System.out.println("输入四位卡号");
Scanner input =new Scanner(System.in);
int kh=input.nextInt();
Random r=new Random();
int a = r.nextInt(10);
if(kh / 100 % 10==a) {
System.out.println("该用户是幸运会员");
}else {
System.out.println("该用户不是幸运会员");
}
}

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"))
else
System.out.println("谢谢使用");
}

public static void reg() {
// 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 upwd=input.next();
System.out.println("注册成功");
returnMain();

}

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 upwd=input.next();
if(uname.equals("zs")&&upwd.equals("123")){
System.out.println("ok");
}else{
System.out.println("fail");
}
returnMain();
}

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