javax.swing.plaf
接口 UIResource

所有已知实现类：

ActionMapUIResource, BasicBorders.ButtonBorder, BasicBorders.FieldBorder, BasicBorders.MarginBorder, BasicBorders.MenuBarBorder, BasicBorders.RadioButtonBorder, BasicBorders.RolloverButtonBorder, BasicBorders.SplitPaneBorder, BasicBorders.ToggleButtonBorder, BasicComboBoxEditor.UIResource, BasicComboBoxRenderer.UIResource, BasicTextUI.BasicCaret, BasicTextUI.BasicHighlighter, BorderUIResource, BorderUIResource.BevelBorderUIResource, BorderUIResource.CompoundBorderUIResource, BorderUIResource.EmptyBorderUIResource, BorderUIResource.EtchedBorderUIResource, BorderUIResource.LineBorderUIResource, BorderUIResource.MatteBorderUIResource, BorderUIResource.TitledBorderUIResource, ColorUIResource, ComponentInputMapUIResource, DefaultListCellRenderer.UIResource, DefaultMenuLayout, DefaultTableCellRenderer.UIResource, DimensionUIResource, FontUIResource, IconUIResource, InputMapUIResource, InsetsUIResource, JScrollPane.ScrollBar, MetalBorders.ButtonBorder, MetalBorders.Flush3DBorder, MetalBorders.InternalFrameBorder, MetalBorders.MenuBarBorder, MetalBorders.MenuItemBorder, MetalBorders.OptionDialogBorder, MetalBorders.PaletteBorder, MetalBorders.PopupMenuBorder, MetalBorders.RolloverButtonBorder, MetalBorders.ScrollPaneBorder, MetalBorders.TextFieldBorder, MetalBorders.ToggleButtonBorder, MetalBorders.ToolBarBorder, MetalCheckBoxIcon, MetalComboBoxEditor.UIResource, MetalIconFactory.PaletteCloseIcon, ScrollPaneLayout.UIResource

public interface UIResource

此接口用于标记由 ComponentUI 委托创建的对象。ComponentUI.installUI() 和 ComponentUI.uninstallUI() 方法可以使用此接口确定属性值是否已经被重写。例如，JList cellRenderer 属性只在其初始值为 null 时由 BasicListUI.installUI() 初始化：

 if (list.getCellRenderer() == null) {
     list.setCellRenderer((ListCellRenderer)(UIManager.get("List.cellRenderer")));
 }
 

在执行 uninstallUI() 时，如果该属性的值是 UIResource 的一个实例，则将该属性重置为 null：

 if (list.getCellRenderer() instanceof UIResource) {
     list.setCellRenderer(null);
 }

此模式应用于除 java.awt.Component 属性 font、foreground 和 background 之外的所有属性。如果这些属性中有一个未被初始化，或者被显式设置为 null，则其容器将提供该值。因此，在调用 installUI() 来动态更新组件外观时， "== null" 是不可靠的。因此，在执行 installUI() 时，要检查当前值是否是一个 UIResource：

 if (!(list.getFont() instanceof UIResource)) {
     list.setFont(UIManager.getFont("List.font"));
 }
 

另请参见：

ComponentUI