Once you have created your components and added them to
containers, the next step is to arrange those components within the
container. This is called layout management and
is almost always performed by a special object known as a
layout manager. Layout managers are
implementations of the
java.awt.LayoutManager interface or its
LayoutManager2 subinterface. Each
implementation enforces a specific layout policy and automatically
arranges the components within a container according to that policy.
The sections that follow demonstrate the use of each of the AWT and
Swing layout managers. Note that
BoxLayout is the only layout manager defined
by Swing. Although Swing defines many new components, Swing GUIs
typically rely on AWT layout managers.
You create a layout manager as you would any other
object. Different layout manager classes take different constructor
arguments to specify the parameters of their layout policy. Once you
create a layout manager, you do not usually invoke its methods.
Instead, you pass the layout manager object to the
setLayout( ) method of the container that is
to be managed; the container invokes the various
LayoutManager methods when necessary. Once
you have set the layout manager, you can usually forget about
As you'll see in the following sections, most of the predefined AWT layout managers have fairly simple layout policies that may not seem like much use on their own. Their power becomes apparent when combined, ...