Requests focus for a component
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();
}
}
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