利用Random生成指定长度的随机数

创建会员账号，会员编号为随机生成的4位数字，创建成功后显示创建的会员信息

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

public class Test3 {

	public static void main(String[] args) {

		Scanner input = new Scanner(System.in);

		System.out.println("请输入会员姓名：");
		String name = input.next();

		String sex = sex();

		int age = age();

		System.out.println("创建会员成功！");
       
		String result = random(4);//4就是给定的固定位数，也可以从键盘输入
		
		System.out.println("会员详细信息：\n姓名：" + name + "\n性别：" + sex + "\n年龄："
				+ age + "\n会员编号：" + result);

	}
//性别
	public static String sex() {
		Scanner input = new Scanner(System.in);
		while (true) {
			System.out.print("请输入会员性别：");
			String sex = input.next();
			if (sex.equals("男") || sex.equals("女")) {
				return sex;
			}else{
				
				System.out.println("性别输入有误，请重新输入！！");
			}
		}
	}
//年龄
	public static int age() {
		Scanner input = new Scanner(System.in);
		while (true) {
			System.out.print("请输入会员年龄：");
			int age = input.nextInt();
			if (age > 0 && age <= 130) {
				return age;
			}else{
				System.out.println("年龄输入有误，请重新输入！！");
			}
		}
	}
//随机数	
	public static String random(int places) {
		StringBuilder num = new StringBuilder();
		Random ran = new Random();
		String new_nums = " ";
		for (int i = 0; i < places; i++) {
			StringBuilder nums = num.append(ran.nextInt(10));
			new_nums = nums.toString();
		}
		return new_nums;
	}
}