Top Description Constructors Methods
javax.swing

public abstract Class LookAndFeel

extends Object
Class Inheritance
Known Direct Subclasses
javax.swing.plaf.basic.BasicLookAndFeel, javax.swing.plaf.multi.MultiLookAndFeel
Imports
java.awt.Font, .Color, .Component, .SystemColor, .Toolkit, java.awt.event.InputEvent, .KeyEvent, sun.awt.SunToolkit, javax.swing.text.*, javax.swing.border.*, javax.swing.plaf.*, java.net.URL, sun.swing.SwingUtilities2, .DefaultLayoutStyle, .ImageIconUIResource, java.util.StringTokenizer

LookAndFeel, as the name implies, encapsulates a look and feel. Beyond installing a look and feel most developers never need to interact directly with LookAndFeel. In general only developers creating a custom look and feel need to concern themselves with this class.

Swing is built upon the foundation that each JComponent subclass has an implementation of a specific ComponentUI subclass. The ComponentUI is often referred to as "the ui", "component ui", or "look and feel delegate". The ComponentUI subclass is responsible for providing the look and feel specific functionality of the component. For example, JTree requires an implementation of the ComponentUI subclass TreeUI. The implementation of the specific ComponentUI subclass is provided by the LookAndFeel. Each JComponent subclass identifies the ComponentUI subclass it requires by way of the JComponent method getUIClassID.

Each LookAndFeel implementation must provide an implementation of the appropriate ComponentUI subclass by specifying a value for each of Swing's ui class ids in the UIDefaults object returned from getDefaults. For example, BasicLookAndFeel uses BasicTreeUI as the concrete implementation for TreeUI. This is accomplished by BasicLookAndFeel providing the key-value pair "TreeUI"-"javax.swing.plaf.basic.BasicTreeUI", in the UIDefaults returned from getDefaults. Refer to UIDefaults#getUI(JComponent) for details on how the implementation of the ComponentUI subclass is obtained.

When a LookAndFeel is installed the UIManager does not check that an entry exists for all ui class ids. As such, random exceptions will occur if the current look and feel has not provided a value for a particular ui class id and an instance of the JComponent subclass is created.

Recommendations for Look and Feels

As noted in UIManager each LookAndFeel has the opportunity to provide a set of defaults that are layered in with developer and system defaults. Some of Swing's components require the look and feel to provide a specific set of defaults. These are documented in the classes that require the specific default.

ComponentUIs and defaults

All ComponentUIs typically need to set various properties on the JComponent the ComponentUI is providing the look and feel for. This is typically done when the ComponentUI is installed on the JComponent. Setting a property should only be done if the developer has not set the property. For non-primitive values it is recommended that the ComponentUI only change the property on the JComponent if the current value is null or implements UIResource. If the current value is null or implements UIResource it indicates the property has not been set by the developer, and the ui is free to change it. For example, BasicButtonUI.installDefaults only changes the font on the JButton if the return value from button.getFont() is null or implements UIResource. On the other hand if button.getFont() returned a non-null value that did not implement UIResource then BasicButtonUI.installDefaults would not change the JButton's font.

For primitive values, such as opaque, the method installProperty should be invoked. installProperty only changes the corresponding property if the value has not been changed by the developer.

ComponentUI implementations should use the various install methods provided by this class as they handle the necessary checking and install the property using the recommended guidelines.

Exceptions

All of the install methods provided by LookAndFeel need to access the defaults if the value of the property being changed is null or a UIResource. For example, installing the font does the following:
  JComponent c;
  Font font = c.getFont();
  if (font == null || (font instanceof UIResource)) {
      c.setFont(UIManager.getFont("fontKey"));
  }
If the font is null or a UIResource, the defaults table is queried with the key fontKey. All of UIDefault's get methods throw a NullPointerException if passed in null. As such, unless otherwise noted each of the various install methods of LookAndFeel throw a NullPointerException if the current value is null or a UIResource and the supplied defaults key is null. In addition, unless otherwise specified all of the install methods throw a NullPointerException if a null component is passed in.
Authors
Tom Ball, Hans Muller
Since
1.2

Constructor Summary

AccessConstructor and Description
protected
LookAndFeel()

Constructor for subclasses to call.

Method Summary

Modifier and TypeMethod and Description
public UIDefaults

Returns:

the look and feel defaults
getDefaults
()

Returns the look and feel defaults.

public abstract String

Returns:

short description for the look and feel
getDescription
()

Return a one line description of this look and feel implementation, e.g. "The CDE/Motif Look and Feel".

public static Object

Returns:

the current value of the desktop property
getDesktopPropertyValue
(String
the name of the system desktop property being queried
systemPropertyName
,
Object
the object to be returned as the value if the system value is null
fallbackValue
)

Returns the value of the specified system desktop property by invoking Toolkit.getDefaultToolkit().getDesktopProperty().

public Icon

Returns:

disabled Icon, or null if a suitable Icon can not be generated
getDisabledIcon
(JComponent
JComponent that will display the Icon, may be null
component
,
Icon
Icon to generate the disabled icon from
icon
)

Returns an Icon with a disabled appearance.

public Icon

Returns:

disabled and selected icon, or null if a suitable Icon can not be generated.
getDisabledSelectedIcon
(JComponent
JComponent that will display the Icon, may be null
component
,
Icon
Icon to generate disabled and selected icon from
icon
)

Returns an Icon for use by disabled components that are also selected.

public abstract String

Returns:

identifier for the look and feel
getID
()

Return a string that identifies this look and feel.

public LayoutStyle

Returns:

the LayoutStyle for this look and feel
getLayoutStyle
()

Returns the LayoutStyle for this look and feel.

public abstract String

Returns:

short identifier for the look and feel
getName
()

Return a short string that identifies this look and feel, e.g. "CDE/Motif".

public boolean

Returns:

true if the RootPaneUI instances created by this look and feel support client side decorations
getSupportsWindowDecorations
()

Returns true if the LookAndFeel returned RootPaneUI instances support providing Window decorations in a JRootPane.

public void
initialize()

Initializes the look and feel.

public static void
installBorder(JComponent
component to set the border on
c
,
String
key specifying the border
defaultBorderName
)

Convenience method for setting a component's border property with a value from the defaults.

public static void
installColors(JComponent
component to set the colors on
c
,
String
key for the background
defaultBgName
,
String
key for the foreground
defaultFgName
)

Convenience method for setting a component's foreground and background color properties with values from the defaults.

public static void
installColorsAndFont(JComponent
component set to the colors and font on
c
,
String
key for the background
defaultBgName
,
String
key for the foreground
defaultFgName
,
String
key for the font
defaultFontName
)

Convenience method for setting a component's foreground, background and font properties with values from the defaults.

public static void
installProperty(JComponent
target component to set the property on
c
,
String
name of the property to set
propertyName
,
Object
value of the property
propertyValue
)

Convenience method for installing a property with the specified name and value on a component if that property has not already been set by the developer.

public abstract boolean

Returns:

true if this look and feel represents the underlying platform look and feel
isNativeLookAndFeel
()

If the underlying platform has a "native" look and feel, and this is an implementation of it, return true.

public abstract boolean

Returns:

true if this is a supported look and feel
isSupportedLookAndFeel
()

Return true if the underlying platform supports and or permits this look and feel.

public static void
loadKeyBindings(InputMap
InputMap to add the key-action pairs to
retMap
,
Object[]
bindings to add to retMap
keys
)

Populates an InputMap with the specified bindings.

public static ComponentInputMap

Returns:

newly created and populated InputMapUIResource
makeComponentInputMap
(JComponent
component to create the ComponentInputMapUIResource with
c
,
Object[]
alternating pairs of keystroke-action key pairs as described in loadKeyBindings
keys
)

Creates a ComponentInputMapUIResource from keys.

public static Object

Returns:

a UIDefaults.LazyValue; when resolved the LazyValue loads the specified image
makeIcon
(final Class<?>
Class used to load the resource
baseClass
,
final String
path to the image to load
gifFile
)

Creates and returns a UIDefault.LazyValue that loads an image.

public static InputMap

Returns:

newly created and populated InputMapUIResource
makeInputMap
(Object[]
alternating pairs of keystroke-action key pairs as described in loadKeyBindings
keys
)

Creates an InputMapUIResource from keys.

public static JTextComponent.KeyBinding[]

Returns:

an array of KeyBindings
makeKeyBindings
(Object[]
an array of key-action pairs
keyBindingList
)

Convenience method for building an array of KeyBindings.

public void
provideErrorFeedback(Component
the Component the error occurred in, may be null indicating the error condition is not directly associated with a Component
component
)

Invoked when the user attempts an invalid operation, such as pasting into an uneditable JTextField that has focus.

public String

Returns:

a String representation of this object
toString
()

Overrides java.lang.Object.toString.

Returns a string that displays and identifies this object's properties.
public void
uninitialize()

Uninitializes the look and feel.

public static void
uninstallBorder(JComponent
component to uninstall the border on
c
)

Convenience method for uninstalling a border.

Inherited from java.lang.Object:
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Constructor Detail

LookAndFeelback to summary
protected LookAndFeel()

Constructor for subclasses to call.

Method Detail

getDefaultsback to summary
public UIDefaults getDefaults()

Returns the look and feel defaults. While this method is public, it should only be invoked by the UIManager when the look and feel is set as the current look and feel and after initialize has been invoked.

Returns:UIDefaults

the look and feel defaults

See Also
initialize, uninitialize, UIManager#setLookAndFeel
getDescriptionback to summary
public abstract String getDescription()

Return a one line description of this look and feel implementation, e.g. "The CDE/Motif Look and Feel". This string is intended for the user, e.g. in the title of a window or in a ToolTip message.

Returns:String

short description for the look and feel

getDesktopPropertyValueback to summary
public static Object getDesktopPropertyValue(String systemPropertyName, Object fallbackValue)

Returns the value of the specified system desktop property by invoking Toolkit.getDefaultToolkit().getDesktopProperty(). If the value of the specified property is null, fallbackValue is returned.

Parameters
systemPropertyName:String

the name of the system desktop property being queried

fallbackValue:Object

the object to be returned as the value if the system value is null

Returns:Object

the current value of the desktop property

Since
1.4
See Also
java.awt.Toolkit#getDesktopProperty
getDisabledIconback to summary
public Icon getDisabledIcon(JComponent component, Icon icon)

Returns an Icon with a disabled appearance. This method is used to generate a disabled Icon when one has not been specified. For example, if you create a JButton and only specify an Icon via setIcon this method will be called to generate the disabled Icon. If null is passed as icon this method returns null.

Some look and feels might not render the disabled Icon, in which case they will ignore this.

Parameters
component:JComponent

JComponent that will display the Icon, may be null

icon:Icon

Icon to generate the disabled icon from

Returns:Icon

disabled Icon, or null if a suitable Icon can not be generated

Since
1.5
getDisabledSelectedIconback to summary
public Icon getDisabledSelectedIcon(JComponent component, Icon icon)

Returns an Icon for use by disabled components that are also selected. This method is used to generate an Icon for components that are in both the disabled and selected states but do not have a specific Icon for this state. For example, if you create a JButton and only specify an Icon via setIcon this method will be called to generate the disabled and selected Icon. If null is passed as icon this methods returns null.

Some look and feels might not render the disabled and selected Icon, in which case they will ignore this.

Parameters
component:JComponent

JComponent that will display the Icon, may be null

icon:Icon

Icon to generate disabled and selected icon from

Returns:Icon

disabled and selected icon, or null if a suitable Icon can not be generated.

Since
1.5
getIDback to summary
public abstract String getID()

Return a string that identifies this look and feel. This string will be used by applications/services that want to recognize well known look and feel implementations. Presently the well known names are "Motif", "Windows", "Mac", "Metal". Note that a LookAndFeel derived from a well known superclass that doesn't make any fundamental changes to the look or feel shouldn't override this method.

Returns:String

identifier for the look and feel

getLayoutStyleback to summary
public LayoutStyle getLayoutStyle()

Returns the LayoutStyle for this look and feel. This never returns null.

You generally don't use the LayoutStyle from the look and feel, instead use the LayoutStyle method getInstance.

Returns:LayoutStyle

the LayoutStyle for this look and feel

Since
1.6
See Also
LayoutStyle#getInstance
getNameback to summary
public abstract String getName()

Return a short string that identifies this look and feel, e.g. "CDE/Motif". This string should be appropriate for a menu item. Distinct look and feels should have different names, e.g. a subclass of MotifLookAndFeel that changes the way a few components are rendered should be called "CDE/Motif My Way"; something that would be useful to a user trying to select a L&F from a list of names.

Returns:String

short identifier for the look and feel

getSupportsWindowDecorationsback to summary
public boolean getSupportsWindowDecorations()

Returns true if the LookAndFeel returned RootPaneUI instances support providing Window decorations in a JRootPane.

The default implementation returns false, subclasses that support Window decorations should override this and return true.

Returns:boolean

true if the RootPaneUI instances created by this look and feel support client side decorations

Since
1.4
See Also
JDialog#setDefaultLookAndFeelDecorated, JFrame#setDefaultLookAndFeelDecorated, JRootPane#setWindowDecorationStyle
initializeback to summary
public void initialize()

Initializes the look and feel. While this method is public, it should only be invoked by the UIManager when a look and feel is installed as the current look and feel. This method is invoked before the UIManager invokes getDefaults. This method is intended to perform any initialization for the look and feel. Subclasses should do any one-time setup they need here, rather than in a static initializer, because look and feel class objects may be loaded just to discover that isSupportedLookAndFeel() returns false.

See Also
uninitialize, UIManager#setLookAndFeel
installBorderback to summary
public static void installBorder(JComponent c, String defaultBorderName)

Convenience method for setting a component's border property with a value from the defaults. The border is only set if the border is null or an instance of UIResource.

Parameters
c:JComponent

component to set the border on

defaultBorderName:String

key specifying the border

Exceptions
NullPointerException:
as described in exceptions
installColorsback to summary
public static void installColors(JComponent c, String defaultBgName, String defaultFgName)

Convenience method for setting a component's foreground and background color properties with values from the defaults. The properties are only set if the current value is either null or a UIResource.

Parameters
c:JComponent

component to set the colors on

defaultBgName:String

key for the background

defaultFgName:String

key for the foreground

Exceptions
NullPointerException:
as described in exceptions
See Also
installColorsAndFont, UIManager#getColor
installColorsAndFontback to summary
public static void installColorsAndFont(JComponent c, String defaultBgName, String defaultFgName, String defaultFontName)

Convenience method for setting a component's foreground, background and font properties with values from the defaults. The properties are only set if the current value is either null or a UIResource.

Parameters
c:JComponent

component set to the colors and font on

defaultBgName:String

key for the background

defaultFgName:String

key for the foreground

defaultFontName:String

key for the font

Exceptions
NullPointerException:
as described in exceptions
See Also
installColors, UIManager#getColor, UIManager#getFont
installPropertyback to summary
public static void installProperty(JComponent c, String propertyName, Object propertyValue)

Convenience method for installing a property with the specified name and value on a component if that property has not already been set by the developer. This method is intended to be used by ui delegate instances that need to specify a default value for a property of primitive type (boolean, int, ..), but do not wish to override a value set by the client. Since primitive property values cannot be wrapped with the UIResource marker, this method uses private state to determine whether the property has been set by the client.

Parameters
c:JComponent

target component to set the property on

propertyName:String

name of the property to set

propertyValue:Object

value of the property

Exceptions
IllegalArgumentException:
if the specified property is not one which can be set using this method
ClassCastException:
if the property value has not been set by the developer and the type does not match the property's type
NullPointerException:
if c is null, or the named property has not been set by the developer and propertyValue is null
Since
1.5
isNativeLookAndFeelback to summary
public abstract boolean isNativeLookAndFeel()

If the underlying platform has a "native" look and feel, and this is an implementation of it, return true. For example, when the underlying platform is Solaris running CDE a CDE/Motif look and feel implementation would return true.

Returns:boolean

true if this look and feel represents the underlying platform look and feel

isSupportedLookAndFeelback to summary
public abstract boolean isSupportedLookAndFeel()

Return true if the underlying platform supports and or permits this look and feel. This method returns false if the look and feel depends on special resources or legal agreements that aren't defined for the current platform.

Returns:boolean

true if this is a supported look and feel

See Also
UIManager#setLookAndFeel
loadKeyBindingsback to summary
public static void loadKeyBindings(InputMap retMap, Object[] keys)

Populates an InputMap with the specified bindings. The bindings are supplied as a list of alternating keystroke-action key pairs. The keystroke is either an instance of KeyStroke, or a String that identifies the KeyStroke for the binding. Refer to KeyStroke.getKeyStroke(String) for the specific format. The action key part of the pair is the key registered in the InputMap for the KeyStroke.

The following illustrates loading an InputMap with two key-action pairs:

  LookAndFeel.loadKeyBindings(inputMap, new Object[] {
    "control X", "cut",
    "control V", "paste"
  });

Supplying a null list of bindings (keys) does not change retMap in any way.

Specifying a null action key results in removing the keystroke's entry from the InputMap. A null keystroke is ignored.

Parameters
retMap:InputMap

InputMap to add the key-action pairs to

keys:Object[]

bindings to add to retMap

Exceptions
NullPointerException:
if keys is non-null, not empty, and retMap is null
Since
1.3
See Also
KeyStroke#getKeyStroke(String), InputMap
makeComponentInputMapback to summary
public static ComponentInputMap makeComponentInputMap(JComponent c, Object[] keys)

Creates a ComponentInputMapUIResource from keys. This is a convenience method for creating a new ComponentInputMapUIResource, invoking loadKeyBindings(map, keys), and returning the ComponentInputMapUIResource.

Parameters
c:JComponent

component to create the ComponentInputMapUIResource with

keys:Object[]

alternating pairs of keystroke-action key pairs as described in loadKeyBindings

Returns:ComponentInputMap

newly created and populated InputMapUIResource

Exceptions
IllegalArgumentException:
if c is null
Since
1.3
See Also
loadKeyBindings, ComponentInputMapUIResource
makeIconback to summary
public static Object makeIcon(final Class<?> baseClass, final String gifFile)

Creates and returns a UIDefault.LazyValue that loads an image. The returned value is an implementation of UIDefaults.LazyValue. When createValue is invoked on the returned object, the image is loaded. If the image is non-null, it is then wrapped in an Icon that implements UIResource. The image is loaded using Class.getResourceAsStream(gifFile).

This method does not check the arguments in any way. It is strongly recommended that non-null values are supplied else exceptions may occur when createValue is invoked on the returned object.

Parameters
baseClass:Class<?>

Class used to load the resource

gifFile:String

path to the image to load

Returns:Object

a UIDefaults.LazyValue; when resolved the LazyValue loads the specified image

See Also
UIDefaults.LazyValue, Icon, Class#getResourceAsStream(String)
makeInputMapback to summary
public static InputMap makeInputMap(Object[] keys)

Creates an InputMapUIResource from keys. This is a convenience method for creating a new InputMapUIResource, invoking loadKeyBindings(map, keys), and returning the InputMapUIResource.

Parameters
keys:Object[]

alternating pairs of keystroke-action key pairs as described in loadKeyBindings

Returns:InputMap

newly created and populated InputMapUIResource

Since
1.3
See Also
loadKeyBindings
makeKeyBindingsback to summary
public static JTextComponent.KeyBinding[] makeKeyBindings(Object[] keyBindingList)

Convenience method for building an array of KeyBindings. While this method is not deprecated, developers should instead use ActionMap and InputMap for supplying key bindings.

This method returns an array of KeyBindings, one for each alternating key-action pair in keyBindingList. A key can either be a String in the format specified by the KeyStroke.getKeyStroke method, or a KeyStroke. The action part of the pair is a String that corresponds to the name of the Action.

The following example illustrates creating a KeyBinding array from six alternating key-action pairs:

 JTextComponent.KeyBinding[] multilineBindings = makeKeyBindings( new Object[] {
         "UP", DefaultEditorKit.upAction,
       "DOWN", DefaultEditorKit.downAction,
    "PAGE_UP", DefaultEditorKit.pageUpAction,
  "PAGE_DOWN", DefaultEditorKit.pageDownAction,
      "ENTER", DefaultEditorKit.insertBreakAction,
        "TAB", DefaultEditorKit.insertTabAction
 });
If keyBindingList's length is odd, the last element is ignored.

Supplying a null value for either the key or action part of the key-action pair results in creating a KeyBinding with the corresponding value null. As other parts of Swing's expect non-null values in a KeyBinding, you should avoid supplying null as either the key or action part of the key-action pair.

Parameters
keyBindingList:Object[]

an array of key-action pairs

Returns:JTextComponent.KeyBinding[]

an array of KeyBindings

Exceptions
NullPointerException:
if keyBindingList is null
ClassCastException:
if the key part of the pair is not a KeyStroke or String, or the action part of the pair is not a String
See Also
ActionMap, InputMap, KeyStroke#getKeyStroke
provideErrorFeedbackback to summary
public void provideErrorFeedback(Component component)

Invoked when the user attempts an invalid operation, such as pasting into an uneditable JTextField that has focus. The default implementation beeps. Subclasses that wish different behavior should override this and provide the additional feedback.

Parameters
component:Component

the Component the error occurred in, may be null indicating the error condition is not directly associated with a Component

Since
1.4
toStringback to summary
public String toString()

Overrides java.lang.Object.toString.

Returns a string that displays and identifies this object's properties.

Returns:String

a String representation of this object

uninitializeback to summary
public void uninitialize()

Uninitializes the look and feel. While this method is public, it should only be invoked by the UIManager when the look and feel is uninstalled. For example, UIManager.setLookAndFeel invokes this when the look and feel is changed.

Subclasses may choose to free up some resources here.

See Also
initialize, UIManager#setLookAndFeel
uninstallBorderback to summary
public static void uninstallBorder(JComponent c)

Convenience method for uninstalling a border. If the border of the component is a UIResource, it is set to null.

Parameters
c:JComponent

component to uninstall the border on

Exceptions
NullPointerException:
if c is null