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Class com.sun.java.swing.BoxLayout

java.lang.Object
   |
   +----com.sun.java.swing.BoxLayout

public class BoxLayout

extends Object

implements LayoutManager2, Serializable

Nesting multiple panels with different combinations of horizontal and vertical gives an effect similar to GridBagLayout, without the complexity. The diagram shows two panels arranged horizontally, each of which contains 3 components arranged vertically.

The Box container uses BoxLayout (unlike JPanel, which defaults to flow layout). You can nest multiple boxes and add components to them to get the arrangement you want.

The BoxLayout 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.

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.

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

X_AXIS

Specifies that components should be laid out left to right.

Y_AXIS

Specifies that components should be laid out top to buttom.

BoxLayout(Container, int)

Creates a layout manager that will lay out components either left to right or top to bottom, as specified in the axis parameter.

addLayoutComponent(Component, Object)

Not used by this class.

addLayoutComponent(String, Component)

Not used by this class.

getLayoutAlignmentX(Container)

Returns the alignment along the X axis for the container.

getLayoutAlignmentY(Container)

Returns the alignment along the Y axis for the container.

invalidateLayout(Container)

Indicates that a child has changed its layout related information, and thus any cached calculations should be flushed.

layoutContainer(Container)

Called by the AWT when the specified container needs to be laid out.

maximumLayoutSize(Container)

Returns the minimum dimensions needed to lay out the components contained in the specified target container.

minimumLayoutSize(Container)

Returns the minimum dimensions needed to lay out the components contained in the specified target container.

preferredLayoutSize(Container)

Returns the preferred dimensions for this layout, given the components in the specified target container.

removeLayoutComponent(Component)

Not used by this class.

 public static final int X_AXIS

Specifies that components should be laid out left to right.

 public static final int Y_AXIS

Specifies that components should be laid out top to buttom.

 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

 public void invalidateLayout(Container target)

Indicates that a child has changed its layout related information, and thus any cached calculations should be flushed.

Parameters:

target - the affected container

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

 public void addLayoutComponent(String name,
                                Component comp)

Not used by this class.

Parameters:

name - the name of the component

comp - the component

 public void removeLayoutComponent(Component comp)

Not used by this class.

Parameters:

comp - the component

 public void addLayoutComponent(Component comp,
                                Object constraints)

Not used by this class.

Parameters:

comp - the component

constraints - constraints

 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

Returns:

the dimensions >= 0 && <= Integer.MAX_VALUE

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

See Also:

Container, minimumLayoutSize, maximumLayoutSize

 public Dimension minimumLayoutSize(Container target)

Returns the minimum dimensions needed to lay out the components contained in the specified target container.

Parameters:

target - the container that needs to be laid out

Returns:

the dimensions >= 0 && <= Integer.MAX_VALUE

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

See Also:

preferredLayoutSize, maximumLayoutSize

 public Dimension maximumLayoutSize(Container target)

Returns the minimum dimensions needed to lay out the components contained in the specified target container.

Parameters:

target - the container that needs to be laid out

Returns:

the dimenions >= 0 && <= Integer.MAX_VALUE

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

See Also:

preferredLayoutSize, minimumLayoutSize

 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.

Parameters:

target - the container

Returns:

the alignment >= 0.0f && <= 1.0f

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

 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.

Parameters:

target - the container

Returns:

the alignment >= 0.0f && <= 1.0f

Throws: AWTError

if the target isn't the container specified to the BoxLayout constructor

 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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