| JavaTM 2 Platform Std. Ed. v1.6.0
javax.swing
Class JLabel
java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.JLabel
- All Implemented Interfaces:
- ImageObserver, MenuContainer, Serializable, Accessible, SwingConstants
- Direct Known Subclasses:
- BasicComboBoxRenderer, DefaultListCellRenderer, DefaultTableCellRenderer, DefaultTreeCellRenderer
public class JLabel - extends JComponent
- implements SwingConstants, Accessible
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 Class Summary |
protected class |
JLabel.AccessibleJLabel
The class used to obtain the accessible role for this object. |
| Fields inherited from interface javax.swing.SwingConstants |
BOTTOM, CENTER, EAST, HORIZONTAL, LEADING, LEFT, NEXT, NORTH, NORTH_EAST, NORTH_WEST, PREVIOUS, RIGHT, SOUTH, SOUTH_EAST, SOUTH_WEST, TOP, TRAILING, VERTICAL, WEST |
|
Constructor Summary |
JLabel()
Creates a JLabel instance with
no image and with an empty string for the title. |
JLabel(Icon image)
Creates a JLabel instance with the specified image. |
JLabel(Icon image,
int horizontalAlignment)
Creates a JLabel instance with the specified
image and horizontal alignment. |
JLabel(String text)
Creates a JLabel instance with the specified text. |
JLabel(String text,
Icon icon,
int horizontalAlignment)
Creates a JLabel instance with the specified
text, image, and horizontal alignment. |
JLabel(String text,
int horizontalAlignment)
Creates a JLabel instance with the specified
text and horizontal alignment. |
|
Method Summary |
protected int |
checkHorizontalKey(int key,
String message)
Verify that key is a legal value for the horizontalAlignment properties. |
protected int |
checkVerticalKey(int key,
String message)
Verify that key is a legal value for the
verticalAlignment or verticalTextPosition properties. |
AccessibleContext |
getAccessibleContext()
Get the AccessibleContext of this object |
Icon |
getDisabledIcon()
Returns the icon used by the label when it's disabled. |
int |
getDisplayedMnemonic()
Return the keycode that indicates a mnemonic key. |
int |
getDisplayedMnemonicIndex()
Returns the character, as an index, that the look and feel should
provide decoration for as representing the mnemonic character. |
int |
getHorizontalAlignment()
Returns the alignment of the label's contents along the X axis. |
int |
getHorizontalTextPosition()
Returns the horizontal position of the label's text,
relative to its image. |
Icon |
getIcon()
Returns the graphic image (glyph, icon) that the label displays. |
int |
getIconTextGap()
Returns the amount of space between the text and the icon
displayed in this label. |
Component |
getLabelFor()
Get the component this is labelling. |
String |
getText()
Returns the text string that the label displays. |
LabelUI |
getUI()
Returns the L&F object that renders this component. |
String |
getUIClassID()
Returns a string that specifies the name of the l&f class
that renders this component. |
int |
getVerticalAlignment()
Returns the alignment of the label's contents along the Y axis. |
int |
getVerticalTextPosition()
Returns the vertical position of the label's text,
relative to its image. |
boolean |
imageUpdate(Image img,
int infoflags,
int x,
int y,
int w,
int h)
This is overridden to return false if the current Icon's Image is
not equal to the passed in Image img. |
protected String |
paramString()
Returns a string representation of this JLabel. |
void |
setDisabledIcon(Icon disabledIcon)
Set the icon to be displayed if this JLabel is "disabled"
(JLabel.setEnabled(false)). |
void |
setDisplayedMnemonic(char aChar)
Specifies the displayedMnemonic as a char value. |
void |
setDisplayedMnemonic(int key)
Specify a keycode that indicates a mnemonic key. |
void |
setDisplayedMnemonicIndex(int index)
Provides a hint to the look and feel as to which character in the
text should be decorated to represent the mnemonic. |
void |
setHorizontalAlignment(int alignment)
Sets the alignment of the label's contents along the X axis. |
void |
setHorizontalTextPosition(int textPosition)
Sets the horizontal position of the label's text,
relative to its image. |
void |
setIcon(Icon icon)
Defines the icon this component will display. |
void |
setIconTextGap(int iconTextGap)
If both the icon and text properties are set, this property
defines the space between them. |
void |
setLabelFor(Component c)
Set the component this is labelling. |
void |
setText(String text)
Defines the single line of text this component will display. |
void |
setUI(LabelUI ui)
Sets the L&F object that renders this component. |
void |
setVerticalAlignment(int alignment)
Sets the alignment of the label's contents along the Y axis. |
void |
setVerticalTextPosition(int textPosition)
Sets the vertical position of the label's text,
relative to its image. |
void |
updateUI()
Resets the UI property to a value from the current look and feel. |
| Methods inherited from class javax.swing.JComponent |
addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getMaximumSize, getMinimumSize, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBackground, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setEnabled, setFocusTraversalKeys, setFont, setForeground, setInheritsPopupMenu, setInputMap, setInputVerifier, setMaximumSize, setMinimumSize, setNextFocusableComponent, setOpaque, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update |
| Methods inherited from class java.awt.Container |
add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, getMousePosition, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusBackward, transferFocusDownCycle, validate, validateTree |
| Methods inherited from class java.awt.Component |
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, createImage, createImage, createVolatileImage, createVolatileImage, disableEvents, dispatchEvent, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, hide, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusUpCycle |
labelFor
protected Component labelFor
JLabel
public JLabel(String text,
Icon icon,
int horizontalAlignment)
- 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.
- Parameters:
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.
JLabel
public JLabel(String text,
int horizontalAlignment)
- Creates a
JLabel instance with the specified
text and horizontal alignment.
The label is centered vertically in its display area.
- Parameters:
text - The text to be displayed by the label.horizontalAlignment - One of the following constants
defined in SwingConstants:
LEFT,
CENTER,
RIGHT,
LEADING or
TRAILING.
JLabel
public JLabel(String text)
- Creates a
JLabel instance with the specified text.
The label is aligned against the leading edge of its display area,
and centered vertically.
- Parameters:
text - The text to be displayed by the label.
JLabel
public JLabel(Icon image,
int horizontalAlignment)
- Creates a
JLabel instance with the specified
image and horizontal alignment.
The label is centered vertically in its display area.
- Parameters:
image - The image to be displayed by the label.horizontalAlignment - One of the following constants
defined in SwingConstants:
LEFT,
CENTER,
RIGHT,
LEADING or
TRAILING.
JLabel
public JLabel(Icon image)
- Creates a
JLabel instance with the specified image.
The label is centered vertically and horizontally
in its display area.
- Parameters:
image - The image to be displayed by the label.
JLabel
public JLabel()
- 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.
getUI
public LabelUI getUI()
- Returns the L&F object that renders this component.
- Returns:
- LabelUI object
setUI
public void setUI(LabelUI ui)
- Sets the L&F object that renders this component.
- Parameters:
ui - the LabelUI L&F object- See Also:
UIDefaults.getUI(javax.swing.JComponent)
updateUI
public void updateUI()
- Resets the UI property to a value from the current look and feel.
- Overrides:
updateUI in class JComponent
- See Also:
JComponent.updateUI()
getUIClassID
public String getUIClassID()
- Returns a string that specifies the name of the l&f class
that renders this component.
- Overrides:
getUIClassID in class JComponent
- Returns:
- String "LabelUI"
- See Also:
JComponent.getUIClassID(),
UIDefaults.getUI(javax.swing.JComponent)
getText
public String getText()
- Returns the text string that the label displays.
- Returns:
- a String
- See Also:
setText(java.lang.String)
setText
public void setText(String text)
- 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.
- See Also:
setVerticalTextPosition(int),
setHorizontalTextPosition(int),
setIcon(javax.swing.Icon)
getIcon
public Icon getIcon()
- Returns the graphic image (glyph, icon) that the label displays.
- Returns:
- an Icon
- See Also:
setIcon(javax.swing.Icon)
setIcon
public void setIcon(Icon icon)
- 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.
- See Also:
setVerticalTextPosition(int),
setHorizontalTextPosition(int),
getIcon()
getDisabledIcon
public Icon getDisabledIcon()
- 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.
- Returns:
- the
disabledIcon property - See Also:
setDisabledIcon(javax.swing.Icon),
LookAndFeel.getDisabledIcon(javax.swing.JComponent, javax.swing.Icon),
ImageIcon
setDisabledIcon
public void setDisabledIcon(Icon disabledIcon)
- Set the icon to be displayed if this JLabel is "disabled"
(JLabel.setEnabled(false)).
The default value of this property is null.
- Parameters:
disabledIcon - the Icon to display when the component is disabled- See Also:
getDisabledIcon(),
JComponent.setEnabled(boolean)
setDisplayedMnemonic
public void setDisplayedMnemonic(int key)
- 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.
- See Also:
getLabelFor(),
setLabelFor(java.awt.Component)
setDisplayedMnemonic
public void setDisplayedMnemonic(char aChar)
- Specifies the displayedMnemonic as a char value.
- Parameters:
aChar - a char specifying the mnemonic to display- See Also:
setDisplayedMnemonic(int)
getDisplayedMnemonic
public int getDisplayedMnemonic()
- Return 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:
- int value for the mnemonic key
- See Also:
getLabelFor(),
setLabelFor(java.awt.Component)
setDisplayedMnemonicIndex
public void setDisplayedMnemonicIndex(int index)
throws IllegalArgumentException
- 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).
- Parameters:
index - Index into the String to underline
- Throws:
IllegalArgumentException - will be thrown if index= length of the text, or < -1- Since:
- 1.4
getDisplayedMnemonicIndex
public int getDisplayedMnemonicIndex()
- Returns the character, as an index, that the look and feel should
provide decoration for as representing the mnemonic character.
- Returns:
- index representing mnemonic character
- Since:
- 1.4
- See Also:
setDisplayedMnemonicIndex(int)
checkHorizontalKey
protected int checkHorizontalKey(int key,
String message)
- Verify that key is a legal value for the horizontalAlignment properties.
- Parameters:
key - the property value to checkmessage - the IllegalArgumentException detail message
- Throws:
IllegalArgumentException - if key isn't LEFT, CENTER, RIGHT,
LEADING or TRAILING.- See Also:
setHorizontalTextPosition(int),
setHorizontalAlignment(int)
checkVerticalKey
protected int checkVerticalKey(int key,
String message)
- Verify that key is a legal value for the
verticalAlignment or verticalTextPosition properties.
- Parameters:
key - the property value to checkmessage - the IllegalArgumentException detail message
- Throws:
IllegalArgumentException - if key isn't TOP, CENTER, or BOTTOM.- See Also:
setVerticalAlignment(int),
setVerticalTextPosition(int)
getIconTextGap
public int getIconTextGap()
- Returns the amount of space between the text and the icon
displayed in this label.
- Returns:
- an int equal to the number of pixels between the text
and the icon.
- See Also:
setIconTextGap(int)
setIconTextGap
public void setIconTextGap(int iconTextGap)
- 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.
- See Also:
getIconTextGap()
getVerticalAlignment
public int getVerticalAlignment()
- Returns the alignment of the label's contents along the Y axis.
- Returns:
- The value of the verticalAlignment property, one of the
following constants defined in
SwingConstants:
TOP,
CENTER, or
BOTTOM. - See Also:
SwingConstants,
setVerticalAlignment(int)
setVerticalAlignment
public void setVerticalAlignment(int alignment)
- Sets the alignment of the label's contents along the Y axis.
The default value of this property is CENTER.
- Parameters:
alignment - One of the following constants
defined in SwingConstants:
TOP,
CENTER (the default), or
BOTTOM.- See Also:
SwingConstants,
getVerticalAlignment()
getHorizontalAlignment
public int getHorizontalAlignment()
- Returns the alignment of the label's contents along the X axis.
- Returns:
- The value of the horizontalAlignment property, one of the
following constants defined in
SwingConstants:
LEFT,
CENTER,
RIGHT,
LEADING or
TRAILING. - See Also:
setHorizontalAlignment(int),
SwingConstants
setHorizontalAlignment
public void setHorizontalAlignment(int alignment)
- Sets the alignment of the label's contents along the X axis.
This is a JavaBeans bound property.
- Parameters:
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.- See Also:
SwingConstants,
getHorizontalAlignment()
getVerticalTextPosition
public int getVerticalTextPosition()
- Returns the vertical position of the label's text,
relative to its image.
- Returns:
- One of the following constants
defined in
SwingConstants:
TOP,
CENTER, or
BOTTOM. - See Also:
setVerticalTextPosition(int),
SwingConstants
setVerticalTextPosition
public void setVerticalTextPosition(int textPosition)
- 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.
- Parameters:
textPosition - One of the following constants
defined in SwingConstants:
TOP,
CENTER (the default), or
BOTTOM.- See Also:
SwingConstants,
getVerticalTextPosition()
getHorizontalTextPosition
public int getHorizontalTextPosition()
- Returns the horizontal position of the label's text,
relative to its image.
- Returns:
- One of the following constants
defined in
SwingConstants:
LEFT,
CENTER,
RIGHT,
LEADING or
TRAILING. - See Also:
SwingConstants
setHorizontalTextPosition
public void setHorizontalTextPosition(int textPosition)
- Sets the horizontal position of the label's text,
relative to its image.
- Parameters:
textPosition - One of the following constants
defined in SwingConstants:
LEFT,
CENTER,
RIGHT,
LEADING, or
TRAILING (the default).
- Throws:
IllegalArgumentException- See Also:
SwingConstants
imageUpdate
public boolean imageUpdate(Image img,
int infoflags,
int x,
int y,
int w,
int h)
- This is overridden to return false if the current Icon's Image is
not equal to the passed in Image
img.
- Specified by:
imageUpdate in interface ImageObserver- Overrides:
imageUpdate in class Component
- Parameters:
img - the image being observedinfoflags - see imageUpdate for more informationx - the x coordinatey - the y coordinatew - the widthh - the height
- Returns:
false if the infoflags indicate that the
image is completely loaded; true otherwise.- See Also:
ImageObserver,
Component.imageUpdate(java.awt.Image, int, int, int, int, int)
paramString
protected String paramString()
- 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.
- Overrides:
paramString in class JComponent
- Returns:
- a string representation of this JLabel.
getLabelFor
public Component getLabelFor()
- Get the component this is labelling.
- Returns:
- 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.
- See Also:
getDisplayedMnemonic(),
setDisplayedMnemonic(int)
setLabelFor
public void setLabelFor(Component c)
- 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.
- Parameters:
c - the Component this label is for, or null if the label is
not the label for a component- See Also:
getDisplayedMnemonic(),
setDisplayedMnemonic(int)
getAccessibleContext
public AccessibleContext getAccessibleContext()
- Get the AccessibleContext of this object
- Specified by:
getAccessibleContext in interface Accessible- Overrides:
getAccessibleContext in class JComponent
- Returns:
- the AccessibleContext of this object
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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