Here you can find the source of isResizable(Window window)
public static boolean isResizable(Window window)
//package com.java2s; //License from project: Apache License import java.awt.Dialog; import java.awt.Window; import javax.swing.JDialog; import javax.swing.JFrame; public class Main { public static boolean isResizable(Window window) { JFrame frame = null;//from ww w .ja v a2 s . co m JDialog dialog = null; if (window instanceof JFrame) { frame = (JFrame) window; return (frame.isResizable() && (frame.getExtendedState() != JFrame.MAXIMIZED_BOTH)); } else if (window instanceof Dialog) { dialog = (JDialog) window; return (dialog != null && dialog.isResizable()); } return false; } }