获取各种随机数的代码工具类

2019-11-09 16:19:58

字体：大中小

来源：转载

供稿：网友

package com.lyt.base.util;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Random;public class RandomUtil {/*** 生成一个n位的随机数字符串* * @param n* @return*/public static String getRandomNum(int length) {String str = "0123456789";Random random = new Random();StringBuffer sb = new StringBuffer();for (int i = 0; i < length; ++i) {int number = random.nextInt(9);// [1,9)sb.append(str.charAt(number+1));}return sb.toString();}/*** 生成一个n位的随机字符串* * @param length* @return*/public static String getRandomString(int length) {String str = "abcdefghijklmnopqrstuvwxyz0123456789";Random random = new Random();StringBuffer sb = new StringBuffer();for (int i = 0; i < length; ++i) {int number = random.nextInt(36);// [0,36)sb.append(str.charAt(number));}return sb.toString();}/*** 获取当前时间，年月日时* * @return*/public static String getDate() {String str = "";DateFormat df = new SimpleDateFormat("yyyyMMddHH");Date date = new Date();str = df.format(date);return str;}/*** 生成用户id，10位,纯数字* * @return*/public static String userId() {String userId = "";userId = getRandomNum(10);return userId;}/*** 生成订单号，13位，纯数字* * @return*/public static String orderId() {String orderId = "";String date = getDate();String rand = getRandomNum(13);orderId = date + rand;return orderId;}/*** 生成商品id，10位,纯数字* * @return*/public static String PRoId() {String userId = "";userId = getRandomNum(10);return userId;}/*** 随机取list数据 * @param list* @param n 取几条* @return*/@SuppressWarnings({ "rawtypes", "unused", "unchecked" })public static List getRandomList(List list, int n) { Map map = new HashMap(); List listNew = new ArrayList(); if(list.size()<=n){ return list; }else{ while(map.size()<n){ int random = (int) (Math.random() * list.size()); if (!map.containsKey(random)) { map.put(random, ""); listNew.add(list.get(random)); } } return listNew; } }/*** 取数组随机数* @param arr* @param n* @return*/@SuppressWarnings({ "unused", "unchecked" })public static Long[] createRandomArray(Long[] arr, int n) { // TODO Auto-generated method stub @SuppressWarnings("rawtypes")Map map = new HashMap(); Long[] arrNew = new Long[n]; if(arr.length<=n){ return arr; }else{ int count = 0;//新数组下标计数 while(map.size()<n){ int random = (int) (Math.random() * arr.length); if (!map.containsKey(random)) { map.put(random, ""); arrNew[count++] = arr[random]; } } return arrNew; } } }

上一篇：将工程打包成library方法

下一篇：grub2中env绑定hook函数

学习交流

索泰发布一款GTX 1070 Mini迷你版本:小机

索泰发布一款GTX 1070 Mini迷你版本:小机箱大爱...

热门图片

猜你喜欢的新闻

猜你喜欢的关注