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Class java.awt.swing.BoxLayout

java.lang.Object
    |
    +----java.awt.swing.BoxLayout

public class BoxLayout
extends Object
implements LayoutManager2, Serializable
A layout manager that places each of its managed components from left to right or from top to bottom. When you create a BoxLayout, you specify whether its major axis is the X axis (which means left to right placement) or Y axis (top to bottom placement). Components are arranged from left to right (or top to bottom), in the same order as they were added to the container.

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Instead of using BoxLayout directly, many programs use the Box class. The Box class provides a lightweight container that uses a BoxLayout. Box also provides handy methods to help you use BoxLayout well.

BoxLayout attempts to arrange components at their preferred widths (for left to right layout) or heights (for top to bottom layout). For a left to right layout, if not all the components are the same height, BoxLayout attempts to make all the components as high as the highest component. If that's not possible for a particular component, then BoxLayout aligns that component vertically, according to the component's Y alignment. By default, a component has an Y alignment of 0.5, which means that the vertical center of the component should have the same Y coordinate as the vertical centers of other components with 0.5 Y alignment.

[A figure and description should go here.]

Similarly, for a vertical layout, BoxLayout attempts to make all components in the column as wide as the widest component; if that fails, it aligns them horizontally according to their X alignments.

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 Swing1.0 applications. It will not be possible to load serialized Swing1.0 objects with future releases of Swing. The JDK1.2 release of Swing will be the compatibility baseline for the serialized form of Swing objects.

See Also:
Box, getAlignmentX, getAlignmentY

Field Summary
static int  X_AXIS
Specifies that components should be laid out left to right.
static int  Y_AXIS
Specifies that components should be laid out top to buttom.
 

Constructor Summary
 BoxLayout(Container target, int axis)
Creates a layout manager that will lay out components either left to right or top to bottom, as specified in the axis parameter.
 

Method Summary
void  addLayoutComponent(String name, Component comp)
Not used by this class.
void  addLayoutComponent(Component comp, Object constraints)
Not used by this class.
float  getLayoutAlignmentX(Container target)
Returns the alignment along the X axis for the container.
float  getLayoutAlignmentY(Container target)
Returns the alignment along the Y axis for the container.
void  invalidateLayout(Container target)
Indicates that a child has changed its layout related information, and thus any cached calculations should be flushed.
void  layoutContainer(Container target)
Called by the AWT when the specified container needs to be laid out.
Dimension  maximumLayoutSize(Container target)
Returns the minimum dimensions needed to lay out the components contained in the specified target container.
Dimension  minimumLayoutSize(Container target)
Returns the minimum dimensions needed to layout the components contained in the specified target container.
Dimension  preferredLayoutSize(Container target)
Returns the preferred dimensions for this layout, given the components in the specified target container.
void  removeLayoutComponent(Component comp)
Not used by this class.
 
Methods inherited from class java.lang.Object
 clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

X_AXIS

public static final int X_AXIS
Specifies that components should be laid out left to right.

Y_AXIS

public static final int Y_AXIS
Specifies that components should be laid out top to buttom.
Constructor Detail

BoxLayout

public BoxLayout(Container target,
                 int axis)
Creates a layout manager that will lay out components either left to right or top to bottom, as specified in the axis parameter.
Parameters:
target - the container that needs to be laid out
axis - the axis to lay out components along. For left-to-right layout, specify BoxLayout.X_AXIS; for top-to-bottom layout, specify BoxLayout.Y_AXIS
Throws:
AWTError - if the value of axis is invalid
Method Detail

invalidateLayout

public void invalidateLayout(Container target)
Indicates that a child has changed its layout related information, and thus any cached calculations should be flushed.
Implements:
invalidateLayout in interface LayoutManager2
Parameters:
target - the affected container
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor

addLayoutComponent

public void addLayoutComponent(String name,
                               Component comp)
Not used by this class.
Implements:
addLayoutComponent in interface LayoutManager2

removeLayoutComponent

public void removeLayoutComponent(Component comp)
Not used by this class.

addLayoutComponent

public void addLayoutComponent(Component comp,
                               Object constraints)
Not used by this class.
Implements:
addLayoutComponent in interface LayoutManager2

preferredLayoutSize

public Dimension preferredLayoutSize(Container target)
Returns the preferred dimensions for this layout, given the components in the specified target container.
Parameters:
target - the container that needs to be laid out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor
See Also:
Container, minimumLayoutSize, maximumLayoutSize

minimumLayoutSize

public Dimension minimumLayoutSize(Container target)
Returns the minimum dimensions needed to layout the components contained in the specified target container.
Parameters:
target - the container that needs to be laid out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor
See Also:
preferredLayoutSize, maximumLayoutSize

maximumLayoutSize

public Dimension maximumLayoutSize(Container target)
Returns the minimum dimensions needed to lay out the components contained in the specified target container.
Implements:
maximumLayoutSize in interface LayoutManager2
Parameters:
target - the container that needs to be laid out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor
See Also:
preferredLayoutSize, minimumLayoutSize

getLayoutAlignmentX

public float getLayoutAlignmentX(Container target)
Returns the alignment along the X axis for the container. If the box is horizontal, the default alignment will be returned. Otherwise, the alignment needed to place the children along the X axis will be returned.
Implements:
getLayoutAlignmentX in interface LayoutManager2
Parameters:
target - the container that needs to be laid out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor

getLayoutAlignmentY

public float getLayoutAlignmentY(Container target)
Returns the alignment along the Y axis for the container. If the box is vertical, the default alignment will be returned. Otherwise, the alignment needed to place the children along the Y axis will be returned.
Implements:
getLayoutAlignmentY in interface LayoutManager2
Parameters:
target - the container that needs to be laid out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor

layoutContainer

public void layoutContainer(Container target)
Called by the AWT when the specified container needs to be laid out.
Parameters:
target - the container to lay out
Throws:
AWTError - if the target isn't the container specified to the BoxLayout constructor

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