public abstract class LookAndFeel extends Object
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 defails 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.
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
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 correspoding 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.
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.Constructor and Description |
---|
LookAndFeel() |
Modifier and Type | Method and Description |
---|---|
UIDefaults |
getDefaults()
Returns the look and feel defaults.
|
abstract String |
getDescription()
Return a one line description of this look and feel implementation,
e.g.
|
static Object |
getDesktopPropertyValue(String systemPropertyName,
Object fallbackValue)
Returns the value of the specified system desktop property by
invoking
Toolkit.getDefaultToolkit().getDesktopProperty() . |
Icon |
getDisabledIcon(JComponent component,
Icon icon)
Returns an
Icon with a disabled appearance. |
Icon |
getDisabledSelectedIcon(JComponent component,
Icon icon)
Returns an
Icon for use by disabled
components that are also selected. |
abstract String |
getID()
Return a string that identifies this look and feel.
|
LayoutStyle |
getLayoutStyle()
Returns the
LayoutStyle for this look
and feel. |
abstract String |
getName()
Return a short string that identifies this look and feel, e.g.
|
boolean |
getSupportsWindowDecorations()
Returns
true if the LookAndFeel returned
RootPaneUI instances support providing Window
decorations in a JRootPane . |
void |
initialize()
Initializes the look and feel.
|
static void |
installBorder(JComponent c,
String defaultBorderName)
Convenience method for setting a component's border property with
a value from the defaults.
|
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.
|
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.
|
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.
|
abstract boolean |
isNativeLookAndFeel()
If the underlying platform has a "native" look and feel, and
this is an implementation of it, return
true . |
abstract boolean |
isSupportedLookAndFeel()
Return
true if the underlying platform supports and or permits
this look and feel. |
static void |
loadKeyBindings(InputMap retMap,
Object[] keys)
Populates an
InputMap with the specified bindings. |
static ComponentInputMap |
makeComponentInputMap(JComponent c,
Object[] keys)
Creates a
ComponentInputMapUIResource from
keys . |
static Object |
makeIcon(Class<?> baseClass,
String gifFile)
Creates and returns a
UIDefault.LazyValue that loads an
image. |
static InputMap |
makeInputMap(Object[] keys)
Creates a
InputMapUIResource from keys . |
static JTextComponent.KeyBinding[] |
makeKeyBindings(Object[] keyBindingList)
Convenience method for building an array of
KeyBindings . |
void |
provideErrorFeedback(Component component)
Invoked when the user attempts an invalid operation,
such as pasting into an uneditable
JTextField
that has focus. |
String |
toString()
Returns a string that displays and identifies this
object's properties.
|
void |
uninitialize()
Uninitializes the look and feel.
|
static void |
uninstallBorder(JComponent c)
Convenience method for uninstalling a border.
|
public static void installColors(JComponent c, String defaultBgName, String defaultFgName)
null
or a UIResource
.c
- component to set the colors ondefaultBgName
- key for the backgrounddefaultFgName
- key for the foregroundNullPointerException
- as described in
exceptionsinstallColorsAndFont(javax.swing.JComponent, java.lang.String, java.lang.String, java.lang.String)
,
UIManager.getColor(java.lang.Object)
public static void installColorsAndFont(JComponent c, String defaultBgName, String defaultFgName, String defaultFontName)
null
or a UIResource
.c
- component set to the colors and font ondefaultBgName
- key for the backgrounddefaultFgName
- key for the foregrounddefaultFontName
- key for the fontNullPointerException
- as described in
exceptionsinstallColors(javax.swing.JComponent, java.lang.String, java.lang.String)
,
UIManager.getColor(java.lang.Object)
,
UIManager.getFont(java.lang.Object)
public static void installBorder(JComponent c, String defaultBorderName)
null
or an instance of UIResource
.c
- component to set the border ondefaultBorderName
- key specifying the borderNullPointerException
- as described in
exceptionspublic static void uninstallBorder(JComponent c)
UIResource
, it is set to null
.c
- component to uninstall the border onNullPointerException
- if c
is null
public static void installProperty(JComponent c, String propertyName, Object propertyValue)
UIResource
marker, this method
uses private state to determine whether the property has been set
by the client.c
- target component to set the property onpropertyName
- name of the property to setpropertyValue
- value of the propertyIllegalArgumentException
- if the specified property is not
one which can be set using this methodClassCastException
- if the property value has not been set
by the developer and the type does not match the property's typeNullPointerException
- if c
is null
, or the
named property has not been set by the developer and
propertyValue
is null
public static JTextComponent.KeyBinding[] makeKeyBindings(Object[] keyBindingList)
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.
keyBindingList
- an array of key-action
pairsKeyBindings
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
ActionMap
,
InputMap
,
KeyStroke.getKeyStroke(char)
public static InputMap makeInputMap(Object[] keys)
InputMapUIResource
from keys
. This is
a convenience method for creating a new InputMapUIResource
,
invoking loadKeyBindings(map, keys)
, and returning the
InputMapUIResource
.keys
- alternating pairs of keystroke-action key
pairs as described in loadKeyBindings(javax.swing.InputMap, java.lang.Object[])
InputMapUIResource
loadKeyBindings(javax.swing.InputMap, java.lang.Object[])
public static ComponentInputMap makeComponentInputMap(JComponent c, Object[] keys)
ComponentInputMapUIResource
from
keys
. This is a convenience method for creating a
new ComponentInputMapUIResource
, invoking loadKeyBindings(map, keys)
, and returning the ComponentInputMapUIResource
.c
- component to create the ComponentInputMapUIResource
withkeys
- alternating pairs of keystroke-action key
pairs as described in loadKeyBindings(javax.swing.InputMap, java.lang.Object[])
InputMapUIResource
IllegalArgumentException
- if c
is null
loadKeyBindings(javax.swing.InputMap, java.lang.Object[])
,
ComponentInputMapUIResource
public static void loadKeyBindings(InputMap retMap, Object[] keys)
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.
retMap
- InputMap
to add the key-action
pairs tokeys
- bindings to add to retMap
NullPointerException
- if keys
is
non-null
, not empty, and retMap
is
null
KeyStroke.getKeyStroke(String)
,
InputMap
public static Object makeIcon(Class<?> baseClass, String gifFile)
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.
baseClass
- Class
used to load the resourcegifFile
- path to the image to loadUIDefaults.LazyValue
; when resolved the
LazyValue
loads the specified imageUIDefaults.LazyValue
,
Icon
,
Class.getResourceAsStream(String)
public LayoutStyle getLayoutStyle()
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
.
LayoutStyle
for this look and feelLayoutStyle.getInstance()
public void provideErrorFeedback(Component component)
JTextField
that has focus. The default implementation beeps. Subclasses
that wish different behavior should override this and provide
the additional feedback.component
- the Component
the error occurred in,
may be null
indicating the error condition is not directly
associated with a Component
public static Object getDesktopPropertyValue(String systemPropertyName, Object fallbackValue)
Toolkit.getDefaultToolkit().getDesktopProperty()
.
If the value of the specified property is null
,
fallbackValue
is returned.systemPropertyName
- the name of the system desktop property being queriedfallbackValue
- the object to be returned as the value if the system value is nullToolkit.getDesktopProperty(java.lang.String)
public Icon getDisabledIcon(JComponent component, Icon icon)
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.
component
- JComponent
that will display the Icon
,
may be null
icon
- Icon
to generate the disabled icon fromIcon
, or null
if a suitable
Icon
can not be generatedpublic Icon getDisabledSelectedIcon(JComponent component, Icon icon)
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.
component
- JComponent
that will display the Icon
,
may be null
icon
- Icon
to generate disabled and selected icon fromnull
if a suitable
Icon
can not be generated.public abstract String getName()
public abstract String getID()
public abstract String getDescription()
public boolean getSupportsWindowDecorations()
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
.
true
if the RootPaneUI
instances created by
this look and feel support client side decorationsJDialog.setDefaultLookAndFeelDecorated(boolean)
,
JFrame.setDefaultLookAndFeelDecorated(boolean)
,
JRootPane.setWindowDecorationStyle(int)
public abstract boolean isNativeLookAndFeel()
true
. For
example, when the underlying platform is Solaris running CDE
a CDE/Motif look and feel implementation would return true
.true
if this look and feel represents the underlying
platform look and feelpublic abstract boolean isSupportedLookAndFeel()
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.true
if this is a supported look and feelUIManager.setLookAndFeel(javax.swing.LookAndFeel)
public void initialize()
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
.public void uninitialize()
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.
public UIDefaults getDefaults()
UIManager
when the
look and feel is set as the current look and feel and after
initialize
has been invoked.initialize()
,
uninitialize()
,
UIManager.setLookAndFeel(javax.swing.LookAndFeel)
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