JavaTM 2 Platform
Standard Edition

Interface UIResource

All Known Implementing Classes:
DefaultListCellRenderer.UIResource, DefaultTableCellRenderer.UIResource, JScrollPane.ScrollBar, ScrollPaneLayout.UIResource, InsetsUIResource, FontUIResource, IconUIResource, BorderUIResource, BorderUIResource.CompoundBorderUIResource, BorderUIResource.EmptyBorderUIResource, BorderUIResource.LineBorderUIResource, BorderUIResource.BevelBorderUIResource, BorderUIResource.EtchedBorderUIResource, BorderUIResource.MatteBorderUIResource, BorderUIResource.TitledBorderUIResource, DimensionUIResource, ColorUIResource, BasicTextUI.BasicCaret, BasicTextUI.BasicHighlighter, BasicComboBoxEditor.UIResource, DefaultMenuLayout, BasicComboBoxRenderer.UIResource, BasicBorders.ButtonBorder, BasicBorders.MenuBarBorder, BasicBorders.MarginBorder, BasicBorders.FieldBorder, BasicBorders.SplitPaneBorder, MetalCheckBoxIcon, MetalBorders.Flush3DBorder, MetalBorders.ButtonBorder, MetalBorders.InternalFrameBorder, MetalBorders.MenuBarBorder, MetalBorders.MenuItemBorder, MetalBorders.PopupMenuBorder, MetalBorders.ToolBarBorder, MetalBorders.ScrollPaneBorder, MetalComboBoxEditor.UIResource

public interface UIResource

This interface is used to mark objects created by ComponentUI delegates. The ComponentUI.installUI() and ComponentUI.uninstallUI() methods can use this interface to decide if a properties value has been overridden. For example, the JList cellRenderer property is initialized by BasicListUI.installUI(), only if it's initial value is null:

 if (list.getCellRenderer() == null) {
At uninstallUI() time we reset the property to null if its value is an instance of UIResource:
 if (list.getCellRenderer() instanceof UIResource) {
This pattern applies to all properties except the java.awt.Component properties font, foreground, and background. If one of these properties isn't initialized, or is explicitly set to null, its container provides the value. For this reason the "== null" is unreliable when installUI() is called to dynamically change a components look and feel. So at installUI() time we check to see if the current value is a UIResource:
 if (!(list.getFont() instanceof UIResource)) {

See Also:

JavaTM 2 Platform
Standard Edition

Submit a bug or feature
Java, Java 2D, and JDBC are a trademarks or registered trademarks of Sun Microsystems, Inc. in the US and other countries.
Copyright 1993-1999 Sun Microsystems, Inc. 901 San Antonio Road,
Palo Alto, California, 94303, U.S.A. All Rights Reserved.