Here you can find the source of getBooleanClientProperty(JComponent c, Object property)
private static boolean getBooleanClientProperty(JComponent c, Object property)
//package com.java2s; /*//w ww . j av a2 s . c om * Copyright (C) 2006 Sun Microsystems, Inc. All rights reserved. Use is * subject to license terms. */ import javax.swing.JComponent; public class Main { private static boolean getBooleanClientProperty(JComponent c, Object property) { Boolean value = (Boolean) c.getClientProperty(property); return (value == null) ? false : value; } }