Here you can find the source of showOnScreen(int screen, JFrame frame)
public static void showOnScreen(int screen, JFrame frame)
//package com.java2s; import java.awt.GraphicsDevice; import java.awt.GraphicsEnvironment; import javax.swing.JFrame; public class Main { public static void showOnScreen(int screen, JFrame frame) { GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); GraphicsDevice[] gs = ge.getScreenDevices(); if (screen >= 0 && screen < gs.length) { //gs[screen].setFullScreenWindow(frame); } else if (gs.length > 0) { // gs[0].setFullScreenWindow(frame); } else {/*from w ww.ja va 2s.c o m*/ throw new RuntimeException("No Screens Found"); } } }