Here you can find the source of joinLong(List
public static String joinLong(List<Long> lst, String prefix)
//package com.java2s; //License from project: Open Source License import java.util.List; public class Main { public static String joinLong(List<Long> lst, String prefix) { final StringBuilder sb = new StringBuilder(); String separator = ""; for (Long f : lst) { sb.append(separator);/* w w w. j a va 2 s .c o m*/ separator = prefix; sb.append(f); } return sb.toString(); } }