Util.java Source code

Introduction

Here is the source code for Util.java

Source

import java.awt.Component;
import java.awt.Container;
import java.awt.FocusTraversalPolicy;
import java.awt.KeyboardFocusManager;

import javax.swing.JComponent;

/**
 * Copyright (C) 2004 NNL Technology AB
 * Visit www.infonode.net for information about InfoNode(R) 
 * products and how to contact NNL Technology AB.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, 
 * MA 02111-1307, USA.
 */

// $Id: ComponentUtil.java,v 1.25 2005/12/04 13:46:04 jesper Exp $

public class Util {
    /**
     * Requests focus for a component. If that's not possible it's
     * {@link FocusTraversalPolicy}is checked. If that doesn't work all it's
     * children is recursively checked with this method.
     *
     * @param component the component to request focus for
     * @return the component which has focus or probably will obtain focus, null
     *         if no component will receive focus
     */
    public static Component smartRequestFocus(Component component) {
        if (requestFocus(component))
            return component;

        if (component instanceof JComponent) {
            FocusTraversalPolicy policy = ((JComponent) component).getFocusTraversalPolicy();

            if (policy != null) {
                Component focusComponent = policy.getDefaultComponent((Container) component);

                if (focusComponent != null && requestFocus(focusComponent)) {
                    return focusComponent;
                }
            }
        }

        if (component instanceof Container) {
            Component[] children = ((Container) component).getComponents();

            for (int i = 0; i < children.length; i++) {
                component = smartRequestFocus(children[i]);

                if (component != null)
                    return component;
            }
        }

        return null;
    }

    /**
     * Requests focus unless the component already has focus. For some weird
     * reason calling {@link Component#requestFocusInWindow()}when the
     * component is focus owner changes focus owner to another component!
     *
     * @param component the component to request focus for
     * @return true if the component has focus or probably will get focus,
     *         otherwise false
     */
    public static boolean requestFocus(Component component) {
        /*
         * System.out.println("Owner: " +
         * System.identityHashCode(KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner()) + ", " +
         * System.identityHashCode(component) + ", " +
         * (KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner() ==
         * component));
         */
        return KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner() == component
                || component.requestFocusInWindow();
    }
}