Java tutorial
//package com.java2s; import java.util.Random; public class Main { public static String getRandomStr() { return getRandomStr(20); } public static String getRandomStr(int len) { Random rd = new Random(); String retStr = ""; do { int rdGet1 = Math.abs(rd.nextInt()) % 10; int rdGet2 = Math.abs(rd.nextInt()) % 26 + 65; retStr = retStr + rdGet1 + (char) rdGet2; } while (retStr.length() < len); return retStr; } }