Layout Managers - The Definitive Guide to Java Swing - page 350

ipadx and ipady specify the internal padding within the component. ipadx specifies the extra
space to the right and left of the component (so the minimum width increases by 2× ipadx pixels).
ipady specifies the extra space above and below the component (so the minimum height increases
by 2× ipady pixels). The difference between insets (external padding) and ipadx / ipady (internal
padding) can be confusing. The insets don't add space to the component itself; they are
external to the component. ipadx and ipady change the component's minimum size, so they
do add space to the component itself.
Weight
weightx and weighty describe how to distribute any additional space within the container.
They allow you to control how components grow (or shrink) when the user resizes the
container, or the container is just bigger to start.
If weightx is 0.0 , the component won't get any additional space available in its row. If one
or more components in a row have a positive weightx , any extra space is distributed propor-
tionally between them. For example, if one component has a weightx value of 1.0 and the
others are all 0.0 , the one component will get all the additional space. If four components in a
row each has a weightx value of 1.0 , and the other components have weightx values of 0.0 , the
four components each get one quarter of the additional space. weighty behaves similarly to
weightx , but in the other direction. Because weightx and weighty control the distribution of
extra space in any row or column, setting either for one component may affect the position of
the other components.
CardLayout Class
The CardLayout layout manager is significantly different from the other layout managers.
Whereas the other layout managers attempt to display all the components within the container
at once, a CardLayout displays only one component at a time. That component can be a component
or container, where the latter lets you see multiple components laid out based on the layout
manager of the embedded container.
Now that the JTabbedPane component (described in the next chapter) is available, CardLayout
is rarely used.
BoxLayout Class
Swing's BoxLayout manager allows you to position components in either a horizontal row or a
vertical column within your own container. In addition to using BoxLayout within your own
container, the Box class (described in the next chapter) offers a container that uses BoxLayout as
its default layout manager.
The benefit of using BoxLayout over something like FlowLayout or GridLayout is that BoxLayout
works to honor each component's x and y alignment properties as well as its maximum size.
And BoxLayout is much easier to use than GridBagLayout . Figure 10-8 demonstrates BoxLayout
in action. Previously, you would have needed to figure out the necessary layout constraints to
get GridBagLayout to behave like this.