Swing I - Java - page 910

Layout Managers
The components that you add to a container class are arranged by an object known as a lay-
out manager . You add a layout manager with the method setLayout , which is a method of
every container class, such as a JFrame or an object of any of the other container classes
that we will introduce later in this chapter. If you do not add a layout manager, a default layout
manager will be provided for you.
SYNTAX
Container_Object .setLayout( new Layout_Manager_Class ());
EXAMPLE (WITHIN A CONSTRUCTOR FOR A CLASS CALLED BorderLayoutJFrame )
public BorderLayoutJFrame()
{
...
setLayout( new BorderLayout());
JLabel label1 = new JLabel("First label");
add(label1, BorderLayout.NORTH);
JLabel label2 = new JLabel("Second label");
add(label2, BorderLayout.SOUTH);
...
}
in Display 17.7 had used the FlowLayout manager instead of the BorderLayout
manager, it would have used the following code:
setLayout( new FlowLayout());
JLabel label1 = new JLabel("First label");
add(label1);
JLabel label2 = new JLabel("Second label");
add(label2);
JLabel label3 = new JLabel("Third label");
add(label3);
Note that if we had used the FlowLayout manager, as in the preceding code, then the
add method would have only one argument. With a FlowLayout manager, the items
are displayed in the order they are added, so that the labels above would be displayed
all on one line as follows:
First label Second label Third label