Java Reference
In-Depth Information
static void invokeLater(Runnable obj )
static void invokeAndWait(Runnable obj )
throws InterruptedException, InvocationTargetException
Ask the Expert
Q :
You state that it is possible to add a component to the other regions of a border
layout by using an overloaded version of add( ) . Can you explain?
A : As explained, BorderLayout implements a layout style that defines five locations to
which a component can be added. The first is the center. The other four are the sides
(i.e., borders), which are called north, south, east, and west. By default, when you
add a component to the content pane, you are adding the component to the center. To
specify one of the other locations, use this form of add( ) :
void add(Component comp , Object loc )
Here, comp is the component to add and loc specifies the location to which it is added.
The loc value is typically one of the following:
In general, BorderLayout is most useful when you are creating a JFrame that contains
a centered component (which might be a group of components held within one of Swing's
lightweight containers) that has a header and/or footer component associated with it. In
other situations, one of Java's other layout managers will be more appropriate.
Here, obj is a Runnable object that will have its run( ) method called by the event-dis-
patching thread. The difference between the two methods is that invokeLater( ) returns im-
mediately, but invokeAndWait( ) waits until obj .run( ) returns. You can use these methods
to call a method that constructs the GUI for your Swing application, or whenever you need
to modify the state of the GUI from code not executed by the event-dispatching thread. You
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