A layout manager that allows multiple components to be laid out either
vertically or horizontally. The components will not wrap so, for
example, a vertical arrangement of components will stay vertically
arranged when the frame is resized.
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 BoxLayout manager is constructed with an axis parameter that
specifies the type of layout that will be done. There are four choices:
X_AXIS - Components are laid out horizontally
from left to right.
Y_AXIS - Components are laid out vertically
from top to bottom.
LINE_AXIS - Components are laid out the way
words are laid out in a line, based on the container's
ComponentOrientation property. If the container's
ComponentOrientation is horizontal then components are laid out
horizontally, otherwise they are laid out vertically. For horizontal
orientations, if the container's ComponentOrientation is left to
right then components are laid out left to right, otherwise they are laid
out right to left. For vertical orientations components are always laid out
from top to bottom.
PAGE_AXIS - Components are laid out the way
text lines are laid out on a page, based on the container's
ComponentOrientation property. If the container's
ComponentOrientation is horizontal then components are laid out
vertically, otherwise they are laid out horizontally. For horizontal
orientations, if the container's ComponentOrientation is left to
right then components are laid out left to right, otherwise they are laid
out right to left. For vertical orientations components are always
laid out from top to bottom.
For all directions, components are arranged in the same order as they were
added to the container.
BoxLayout attempts to arrange components
at their preferred widths (for horizontal layout)
or heights (for vertical layout).
For a horizontal 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 a 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. For PAGE_AXIS
layout,
horizontal alignment is done based on the leading edge of the component.
In other words, an X alignment value of 0.0 means the left edge of a
component if the container's ComponentOrientation
is left to
right and it means the right edge of the component otherwise.
Instead of using BoxLayout directly, many programs use the Box class.
The Box class is a lightweight container that uses a BoxLayout.
It also provides handy methods to help you use BoxLayout well.
Adding components to multiple nested boxes is a powerful way to get
the arrangement you want.
For further information and examples see
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 JavaBeansTM
has been added to the java.beans
package.
Please see XMLEncoder
.