java.lang.Object | ||||
↳ | java.awt.Component | |||
↳ | java.awt.Container | |||
↳ | javax.swing.JComponent | |||
↳ | javax.swing.JLabel |
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A display area for a short text string or an image, or both. A label does not react to input events. As a result, it cannot get the keyboard focus. A label can, however, display a keyboard alternative as a convenience for a nearby component that has a keyboard alternative but can't display it.
A JLabel
object can display
either text, an image, or both.
You can specify where in the label's display area
the label's contents are aligned
by setting the vertical and horizontal alignment.
By default, labels are vertically centered
in their display area.
Text-only labels are leading edge aligned, by default;
image-only labels are horizontally centered, by default.
You can also specify the position of the text relative to the image. By default, text is on the trailing edge of the image, with the text and image vertically aligned.
A label's leading and trailing edge are determined from the value of its
ComponentOrientation
property. At present, the default
ComponentOrientation setting maps the leading edge to left and the trailing
edge to right.
Finally, you can use the setIconTextGap
method
to specify how many pixels
should appear between the text and the image.
The default is 4 pixels.
See How to Use Labels in The Java Tutorial for further documentation.
Warning: Swing is not thread safe. For more information see Swing's Threading Policy.
Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing. As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans
package.
Please see XMLEncoder
.
Nested Classes | |||||||||||
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JLabel.AccessibleJLabel | The class used to obtain the accessible role for this object. |
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Inherited Constants | |||||||||||
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Fields | |||||||||||
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labelFor |
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Inherited Fields | |||||||||||
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Public Constructors | |||||||||||
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Creates a
JLabel instance with the specified
text, image, and horizontal alignment. | |||||||||||
Creates a
JLabel instance with the specified
text and horizontal alignment. | |||||||||||
Creates a
JLabel instance with the specified text. | |||||||||||
Creates a
JLabel instance with the specified
image and horizontal alignment. | |||||||||||
Creates a
JLabel instance with the specified image. | |||||||||||
Creates a
JLabel instance with
no image and with an empty string for the title. |
Public Methods | |||||||||||
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Get the AccessibleContext of this object
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Returns the icon used by the label when it's disabled.
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Return the keycode that indicates a mnemonic key.
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Returns the character, as an index, that the look and feel should
provide decoration for as representing the mnemonic character.
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Returns the alignment of the label's contents along the X axis.
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Returns the horizontal position of the label's text,
relative to its image.
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Returns the graphic image (glyph, icon) that the label displays.
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Returns the amount of space between the text and the icon
displayed in this label.
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Get the component this is labelling.
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Returns the text string that the label displays.
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Returns the L&F object that renders this component.
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Returns a string that specifies the name of the l&f class
that renders this component.
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Returns the alignment of the label's contents along the Y axis.
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Returns the vertical position of the label's text,
relative to its image.
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This is overridden to return false if the current Icon's Image is
not equal to the passed in Image
img . | |||||||||||
Set the icon to be displayed if this JLabel is "disabled"
(JLabel.setEnabled(false)).
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Specify a keycode that indicates a mnemonic key.
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Specifies the displayedMnemonic as a char value.
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Provides a hint to the look and feel as to which character in the
text should be decorated to represent the mnemonic.
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Sets the alignment of the label's contents along the X axis.
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Sets the horizontal position of the label's text,
relative to its image.
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Defines the icon this component will display.
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If both the icon and text properties are set, this property
defines the space between them.
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Set the component this is labelling.
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Defines the single line of text this component will display.
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Sets the L&F object that renders this component.
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Sets the alignment of the label's contents along the Y axis.
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Sets the vertical position of the label's text,
relative to its image.
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Resets the UI property to a value from the current look and feel.
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Protected Methods | |||||||||||
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Verify that key is a legal value for the horizontalAlignment properties.
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Verify that key is a legal value for the
verticalAlignment or verticalTextPosition properties.
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Returns a string representation of this JLabel.
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Inherited Methods | |||||||||||
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Creates a JLabel
instance with the specified
text, image, and horizontal alignment.
The label is centered vertically in its display area.
The text is on the trailing edge of the image.
text | The text to be displayed by the label. |
---|---|
icon | The image to be displayed by the label. |
horizontalAlignment | One of the following constants
defined in SwingConstants :
LEFT ,
CENTER ,
RIGHT ,
LEADING or
TRAILING .
|
Creates a JLabel
instance with the specified
text and horizontal alignment.
The label is centered vertically in its display area.
text | The text to be displayed by the label. |
---|---|
horizontalAlignment | One of the following constants
defined in SwingConstants :
LEFT ,
CENTER ,
RIGHT ,
LEADING or
TRAILING .
|
Creates a JLabel
instance with the specified text.
The label is aligned against the leading edge of its display area,
and centered vertically.
text | The text to be displayed by the label. |
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Creates a JLabel
instance with the specified
image and horizontal alignment.
The label is centered vertically in its display area.
image | The image to be displayed by the label. |
---|---|
horizontalAlignment | One of the following constants
defined in SwingConstants :
LEFT ,
CENTER ,
RIGHT ,
LEADING or
TRAILING .
|
Creates a JLabel
instance with the specified image.
The label is centered vertically and horizontally
in its display area.
image | The image to be displayed by the label. |
---|
Creates a JLabel
instance with
no image and with an empty string for the title.
The label is centered vertically
in its display area.
The label's contents, once set, will be displayed on the leading edge
of the label's display area.
Get the AccessibleContext of this object
Returns the icon used by the label when it's disabled. If no disabled icon has been set this will forward the call to the look and feel to construct an appropriate disabled Icon.
Some look and feels might not render the disabled Icon, in which case they will ignore this.
disabledIcon
propertyReturn the keycode that indicates a mnemonic key. This property is used when the label is part of a larger component. If the labelFor property of the label is not null, the label will call the requestFocus method of the component specified by the labelFor property when the mnemonic is activated.
Returns the character, as an index, that the look and feel should provide decoration for as representing the mnemonic character.
Returns the alignment of the label's contents along the X axis.
SwingConstants
:
LEFT
,
CENTER
,
RIGHT
,
LEADING
or
TRAILING
.Returns the horizontal position of the label's text, relative to its image.
SwingConstants
:
LEFT
,
CENTER
,
RIGHT
,
LEADING
or
TRAILING
.Returns the graphic image (glyph, icon) that the label displays.
Returns the amount of space between the text and the icon displayed in this label.
Get the component this is labelling.
Returns a string that specifies the name of the l&f class that renders this component.
Returns the alignment of the label's contents along the Y axis.
SwingConstants
:
TOP
,
CENTER
, or
BOTTOM
.Returns the vertical position of the label's text, relative to its image.
SwingConstants
:
TOP
,
CENTER
, or
BOTTOM
.This is overridden to return false if the current Icon's Image is
not equal to the passed in Image img
.
img | the image being observed |
---|---|
infoflags | see imageUpdate for more information |
x | the x coordinate |
y | the y coordinate |
w | the width |
h | the height |
false
if the infoflags indicate that the
image is completely loaded; true
otherwise.Set the icon to be displayed if this JLabel is "disabled" (JLabel.setEnabled(false)).
The default value of this property is null.
disabledIcon | the Icon to display when the component is disabled |
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Specify a keycode that indicates a mnemonic key. This property is used when the label is part of a larger component. If the labelFor property of the label is not null, the label will call the requestFocus method of the component specified by the labelFor property when the mnemonic is activated.
Specifies the displayedMnemonic as a char value.
aChar | a char specifying the mnemonic to display |
---|
Provides a hint to the look and feel as to which character in the text should be decorated to represent the mnemonic. Not all look and feels may support this. A value of -1 indicates either there is no mnemonic, the mnemonic character is not contained in the string, or the developer does not wish the mnemonic to be displayed.
The value of this is updated as the properties relating to the
mnemonic change (such as the mnemonic itself, the text...).
You should only ever have to call this if
you do not wish the default character to be underlined. For example, if
the text was 'Save As', with a mnemonic of 'a', and you wanted the 'A'
to be decorated, as 'Save As', you would have to invoke
setDisplayedMnemonicIndex(5)
after invoking
setDisplayedMnemonic(KeyEvent.VK_A)
.
index | Index into the String to underline |
---|
IllegalArgumentException | will be thrown if index = length of the text, or < -1 |
---|
Sets the alignment of the label's contents along the X axis.
This is a JavaBeans bound property.
alignment | One of the following constants
defined in SwingConstants :
LEFT ,
CENTER (the default for image-only labels),
RIGHT ,
LEADING (the default for text-only labels) or
TRAILING . |
---|
Sets the horizontal position of the label's text, relative to its image.
textPosition | One of the following constants
defined in SwingConstants :
LEFT ,
CENTER ,
RIGHT ,
LEADING , or
TRAILING (the default). |
---|
IllegalArgumentException |
Defines the icon this component will display. If the value of icon is null, nothing is displayed.
The default value of this property is null.
This is a JavaBeans bound property.
If both the icon and text properties are set, this property defines the space between them.
The default value of this property is 4 pixels.
This is a JavaBeans bound property.
Set the component this is labelling. Can be null if this does not label a Component. If the displayedMnemonic property is set and the labelFor property is also set, the label will call the requestFocus method of the component specified by the labelFor property when the mnemonic is activated.
c | the Component this label is for, or null if the label is not the label for a component |
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Defines the single line of text this component will display. If the value of text is null or empty string, nothing is displayed.
The default value of this property is null.
This is a JavaBeans bound property.
Sets the L&F object that renders this component.
ui | the LabelUI L&F object |
---|
Sets the alignment of the label's contents along the Y axis.
The default value of this property is CENTER.
alignment | One of the following constants
defined in SwingConstants :
TOP ,
CENTER (the default), or
BOTTOM . |
---|
Sets the vertical position of the label's text, relative to its image.
The default value of this property is CENTER.
This is a JavaBeans bound property.
textPosition | One of the following constants
defined in SwingConstants :
TOP ,
CENTER (the default), or
BOTTOM . |
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Resets the UI property to a value from the current look and feel.
Verify that key is a legal value for the horizontalAlignment properties.
key | the property value to check |
---|---|
message | the IllegalArgumentException detail message |
IllegalArgumentException | if key isn't LEFT, CENTER, RIGHT, LEADING or TRAILING. |
---|
Verify that key is a legal value for the verticalAlignment or verticalTextPosition properties.
key | the property value to check |
---|---|
message | the IllegalArgumentException detail message |
IllegalArgumentException | if key isn't TOP, CENTER, or BOTTOM. |
---|
Returns a string representation of this JLabel. This method
is intended to be used only for debugging purposes, and the
content and format of the returned string may vary between
implementations. The returned string may be empty but may not
be null
.