Class NullLabel

  • All Implemented Interfaces:
    java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable, javax.accessibility.Accessible, javax.swing.SwingConstants

    public class NullLabel
    extends javax.swing.JLabel
    This is part of the null-components. A null component doesn't have foreground, background or font value set. In the other words, the foreground, background and font value of null-component are null. But this doesn't mean getBackground(), getForeground() or getFont() will return null. According to Component.getBackground(), Component.getForeground() and Component.getFont(), if the value is null, it will get the value from its parent. In the other words, if you add a null-component to JPanel, you can use JPanel to control the background, foreground and font of this null-component. The feature is very helpful if you want to make sure all components in a JPanel has the same background, foreground or font.

    Even in null-components, you can still change the foreground, background or font value if you do want. However, you'll have to use a font which is not an instance of FontUIResource or a color which is not an instance of ColorUIResource.

    We creates a few null-components. It doesn't cover all components. You can always create your own. All you need to do is this

    
     public class NullXxxComponent extends XxxComponent {
         // invoke clearAttribute() in all the constructors
     

    public void setFont(Font font) { if (font instanceof FontUIResource) { return; } super.setFont(font); }

    public void setBackground(Color bg) { if (bg instanceof ColorUIResource) { return; } super.setBackground(bg); }

    public void setForeground(Color fg) { if (fg instanceof ColorUIResource) { return; } super.setForeground(fg); }

    private void clearAttribute() { setFont(null); setBackground(null); // do not do this for JButton since JButton always paints button // content background. So it'd better to leave the foreground alone setForeground(null); } }

    See Also:
    NullButton, NullCheckBox, NullJideButton, NullPanel, NullRadioButton, NullTristateCheckBox, Serialized Form
    • Nested Class Summary

      • Nested classes/interfaces inherited from class javax.swing.JLabel

        javax.swing.JLabel.AccessibleJLabel
      • Nested classes/interfaces inherited from class javax.swing.JComponent

        javax.swing.JComponent.AccessibleJComponent
      • Nested classes/interfaces inherited from class java.awt.Container

        java.awt.Container.AccessibleAWTContainer
      • Nested classes/interfaces inherited from class java.awt.Component

        java.awt.Component.AccessibleAWTComponent, java.awt.Component.BaselineResizeBehavior, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy
    • Field Summary

      • Fields inherited from class javax.swing.JLabel

        labelFor
      • Fields inherited from class javax.swing.JComponent

        listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW
      • Fields inherited from class java.awt.Component

        accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
      • Fields inherited from interface java.awt.image.ImageObserver

        ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
      • 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

      Constructors 
      Constructor Description
      NullLabel()  
      NullLabel​(java.lang.String text)  
      NullLabel​(java.lang.String text, int horizontalAlignment)  
      NullLabel​(java.lang.String text, javax.swing.Icon icon, int horizontalAlignment)  
      NullLabel​(javax.swing.Icon image)  
      NullLabel​(javax.swing.Icon image, int horizontalAlignment)  
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void setBackground​(java.awt.Color bg)  
      void setFont​(java.awt.Font font)  
      void setForeground​(java.awt.Color fg)  
      • Methods inherited from class javax.swing.JLabel

        checkHorizontalKey, checkVerticalKey, getAccessibleContext, getDisabledIcon, getDisplayedMnemonic, getDisplayedMnemonicIndex, getHorizontalAlignment, getHorizontalTextPosition, getIcon, getIconTextGap, getLabelFor, getText, getUI, getUIClassID, getVerticalAlignment, getVerticalTextPosition, imageUpdate, paramString, setDisabledIcon, setDisplayedMnemonic, setDisplayedMnemonic, setDisplayedMnemonicIndex, setHorizontalAlignment, setHorizontalTextPosition, setIcon, setIconTextGap, setLabelFor, setText, setUI, setVerticalAlignment, setVerticalTextPosition, updateUI
      • 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, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, 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, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setEnabled, setFocusTraversalKeys, 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, 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, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, 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, requestFocus, requestFocus, requestFocusInWindow, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setMixingCutoutShape, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Constructor Detail

      • NullLabel

        public NullLabel()
      • NullLabel

        public NullLabel​(java.lang.String text,
                         javax.swing.Icon icon,
                         int horizontalAlignment)
      • NullLabel

        public NullLabel​(java.lang.String text,
                         int horizontalAlignment)
      • NullLabel

        public NullLabel​(java.lang.String text)
      • NullLabel

        public NullLabel​(javax.swing.Icon image,
                         int horizontalAlignment)
      • NullLabel

        public NullLabel​(javax.swing.Icon image)
    • Method Detail

      • setFont

        public void setFont​(java.awt.Font font)
        Overrides:
        setFont in class javax.swing.JComponent
      • setBackground

        public void setBackground​(java.awt.Color bg)
        Overrides:
        setBackground in class javax.swing.JComponent
      • setForeground

        public void setForeground​(java.awt.Color fg)
        Overrides:
        setForeground in class javax.swing.JComponent