Here you can find the source of joinMap(Map, ?> map)
public static String joinMap(Map<?, ?> map)
//package com.java2s; //License from project: LGPL import java.util.Map; public class Main { public static String joinMap(Map<?, ?> map) { if (map.isEmpty()) { return ""; }//w w w . j av a2s . c o m StringBuilder stringBuilder = new StringBuilder(); boolean notFirst = false; for (Map.Entry<?, ?> entry : map.entrySet()) { if (notFirst) { stringBuilder.append(','); } stringBuilder.append(entry.getKey().toString()).append(':').append(entry.getValue().toString()); notFirst = true; } return stringBuilder.toString(); } }