Here you can find the source of addToQue(JFrame frame)
synchronized private static void addToQue(JFrame frame)
//package com.java2s; //License from project: Open Source License import java.util.ArrayList; import javax.swing.JFrame; public class Main { private static ArrayList<JFrame> reaktivationQue = new ArrayList<>(); synchronized private static void addToQue(JFrame frame) { reaktivationQue.add(frame);//from w w w .ja v a 2 s. com } }