Module java.desktop
Package javax.swing

# Class Box

java.lang.Object
java.awt.Component
java.awt.Container
javax.swing.JComponent
javax.swing.Box

All Implemented Interfaces:
  `ImageObserver`, `MenuContainer`, `Serializable`, `Accessible`

@JavaBean(defaultProperty="accessibleContext") public class Box extends JComponent implements Accessible
A lightweight container that uses a BoxLayout object as its layout manager. Box provides several class methods that are useful for containers using BoxLayout -- even non-Box containers.

The `Box` class can create several kinds of invisible components that affect layout: glue, struts, and rigid areas. If all the components your `Box` contains have a fixed size, you might want to use a glue component (returned by `createGlue`) to control the components' positions. If you need a fixed amount of space between two components, try using a strut (`createHorizontalStrut` or `createVerticalStrut`). If you need an invisible component that always takes up the same amount of space, get it by invoking `createRigidArea`.

If you are implementing a `BoxLayout` you can find further information and examples in How to Use BoxLayout, a section in The Java Tutorial.

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 JavaBeans has been added to the `java.beans` package. Please see `XMLEncoder`.

Since:
  1.2
See Also:
  - `BoxLayout`

- ## Nested Class Summary

  Nested Classes
  Modifier and Type
  Class
  Description
  `protected class`
  `Box.AccessibleBox`
  This class implements accessibility support for the `Box` class.
  `static class`
  `Box.Filler`
  An implementation of a lightweight component that participates in layout but has no view.

  ## Nested classes/interfaces declared in class javax.swing.JComponent

  `JComponent.AccessibleJComponent`

  ## Nested classes/interfaces declared in class java.awt.Container

  `Container.AccessibleAWTContainer`

  ## Nested classes/interfaces declared in class java.awt.Component

  `Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy`

- ## Field Summary

  ### Fields declared in class javax.swing.JComponent

  `listenerList, TOOL_TIP_TEXT_KEY, ui, UNDEFINED_CONDITION, WHEN_ANCESTOR_OF_FOCUSED_COMPONENT, WHEN_FOCUSED, WHEN_IN_FOCUSED_WINDOW`

  ### Fields declared in class java.awt.Component

  `accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT`

  ### Fields declared in interface java.awt.image.ImageObserver

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

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `Box(int axis)`
  Creates a `Box` that displays its components along the specified axis.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static Component`
  `createGlue()`
  Creates an invisible "glue" component that can be useful in a Box whose visible components have a maximum width (for a horizontal box) or height (for a vertical box).
  `static Box`
  `createHorizontalBox()`
  Creates a `Box` that displays its components from left to right.
  `static Component`
  `createHorizontalGlue()`
  Creates a horizontal glue component.
  `static Component`
  `createHorizontalStrut(int width)`
  Creates an invisible, fixed-width component.
  `static Component`
  `createRigidArea(Dimension d)`
  Creates an invisible component that's always the specified size.
  `static Box`
  `createVerticalBox()`
  Creates a `Box` that displays its components from top to bottom.
  `static Component`
  `createVerticalGlue()`
  Creates a vertical glue component.
  `static Component`
  `createVerticalStrut(int height)`
  Creates an invisible, fixed-height component.
  `AccessibleContext`
  `getAccessibleContext()`
  Gets the AccessibleContext associated with this Box.
  `protected void`
  `paintComponent(Graphics g)`
  Paints this `Box`.
  `void`
  `setLayout(LayoutManager l)`
  Throws an AWTError, since a Box can use only a BoxLayout.

  ### Methods declared in class javax.swing.JComponent

  `addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, 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, getUI, getUIClassID, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintImmediately, paintImmediately, paramString, 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, updateUI`

  ### Methods declared in 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, transferFocusDownCycle, validate, validateTree`

  ### Methods declared in 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, 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, imageUpdate, 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 declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### Box

    public Box(int axis)
    Creates a `Box` that displays its components along the specified axis.
    Parameters:
      `axis` - can be `BoxLayout.X_AXIS`, `BoxLayout.Y_AXIS`, `BoxLayout.LINE_AXIS` or `BoxLayout.PAGE_AXIS`.
    Throws:
      `AWTError` - if the `axis` is invalid
    See Also:
      - `createHorizontalBox()`
      - `createVerticalBox()`

- ## Method Details

  - ### createHorizontalBox

    public static Box createHorizontalBox()
    Creates a `Box` that displays its components from left to right. If you want a `Box` that respects the component orientation you should create the `Box` using the constructor and pass in `BoxLayout.LINE_AXIS`, eg:

           Box lineBox = new Box(BoxLayout.LINE_AXIS);

    Returns:
      the box

  - ### createVerticalBox

    public static Box createVerticalBox()
    Creates a `Box` that displays its components from top to bottom. If you want a `Box` that respects the component orientation you should create the `Box` using the constructor and pass in `BoxLayout.PAGE_AXIS`, eg:

           Box lineBox = new Box(BoxLayout.PAGE_AXIS);

    Returns:
      the box

  - ### createRigidArea

    public static Component createRigidArea(Dimension d)
    Creates an invisible component that's always the specified size.
    Parameters:
      `d` - the dimensions of the invisible component
    Returns:
      the component
    See Also:
      - `createGlue()`
      - `createHorizontalStrut(int)`
      - `createVerticalStrut(int)`

  - ### createHorizontalStrut

    public static Component createHorizontalStrut(int width)
    Creates an invisible, fixed-width component. In a horizontal box, you typically use this method to force a certain amount of space between two components. In a vertical box, you might use this method to force the box to be at least the specified width. The invisible component has no height unless excess space is available, in which case it takes its share of available space, just like any other component that has no maximum height.
    Parameters:
      `width` - the width of the invisible component, in pixels >= 0
    Returns:
      the component
    See Also:
      - `createVerticalStrut(int)`
      - `createGlue()`
      - `createRigidArea(java.awt.Dimension)`

  - ### createVerticalStrut

    public static Component createVerticalStrut(int height)
    Creates an invisible, fixed-height component. In a vertical box, you typically use this method to force a certain amount of space between two components. In a horizontal box, you might use this method to force the box to be at least the specified height. The invisible component has no width unless excess space is available, in which case it takes its share of available space, just like any other component that has no maximum width.
    Parameters:
      `height` - the height of the invisible component, in pixels >= 0
    Returns:
      the component
    See Also:
      - `createHorizontalStrut(int)`
      - `createGlue()`
      - `createRigidArea(java.awt.Dimension)`

  - ### createGlue

    public static Component createGlue()
    Creates an invisible "glue" component that can be useful in a Box whose visible components have a maximum width (for a horizontal box) or height (for a vertical box). You can think of the glue component as being a gooey substance that expands as much as necessary to fill the space between its neighboring components.

    For example, suppose you have a horizontal box that contains two fixed-size components. If the box gets extra space, the fixed-size components won't become larger, so where does the extra space go? Without glue, the extra space goes to the right of the second component. If you put glue between the fixed-size components, then the extra space goes there. If you put glue before the first fixed-size component, the extra space goes there, and the fixed-size components are shoved against the right edge of the box. If you put glue before the first fixed-size component and after the second fixed-size component, the fixed-size components are centered in the box.

    To use glue, call `Box.createGlue` and add the returned component to a container. The glue component has no minimum or preferred size, so it takes no space unless excess space is available. If excess space is available, then the glue component takes its share of available horizontal or vertical space, just like any other component that has no maximum width or height.

    Returns:
      the component

  - ### createHorizontalGlue

    public static Component createHorizontalGlue()
    Creates a horizontal glue component.
    Returns:
      the component

  - ### createVerticalGlue

    public static Component createVerticalGlue()
    Creates a vertical glue component.
    Returns:
      the component

  - ### setLayout

    public void setLayout(LayoutManager l)
    Throws an AWTError, since a Box can use only a BoxLayout.
    Overrides:
      `setLayout` in class `Container`
    Parameters:
      `l` - the layout manager to use
    See Also:
      - `Container.doLayout()`
      - `Container.getLayout()`
      - `Container.invalidate()`

  - ### paintComponent

    protected void paintComponent(Graphics g)
    Paints this `Box`. If this `Box` has a UI this method invokes super's implementation, otherwise if this `Box` is opaque the `Graphics` is filled using the background.
    Overrides:
      `paintComponent` in class `JComponent`
    Parameters:
      `g` - the `Graphics` to paint to
    Throws:
      `NullPointerException` - if `g` is null
    Since:
      1.6
    See Also:
      - `JComponent.paint(java.awt.Graphics)`
      - `ComponentUI`

  - ### getAccessibleContext

    @BeanProperty(bound=false) public AccessibleContext getAccessibleContext()
    Gets the AccessibleContext associated with this Box. For boxes, the AccessibleContext takes the form of an AccessibleBox. A new AccessibleAWTBox instance is created if necessary.
    Specified by:
      `getAccessibleContext` in interface `Accessible`
    Overrides:
      `getAccessibleContext` in class `Component`
    Returns:
      an AccessibleBox that serves as the AccessibleContext of this Box