Swing I - Absolute Java - page 965

Display 17.8 BorderLayout Regions

BorderLayout.NORTH

BorderLayout.
EAST

BorderLayout.
WEST

BorderLayout.CENTER

BorderLayout.SOUTH

In Display 17.7 , we added labels as follows:

JLabel label1 = new JLabel("First label");
add(label1, BorderLayout.NORTH);

JLabel label2 = new JLabel("Second label");
add(label2, BorderLayout.SOUTH);

JLabel label3 = new JLabel("Third label");
add(label3, BorderLayout.CENTER);
When you use a BorderLayout manager, you give the location of the component
added as a second argument to the method add , as in the following:

add(label1, BorderLayout.NORTH);
The labels (or other components to be added) need not be added in any particular
order, because the second argument completely specifies where the label is placed.
BorderLayout.NORTH , BorderLayout.SOUTH , BorderLayout.EAST , Border
Layout.WEST , and BorderLayout.CENTER are five string constants defined in the
class BorderLayout . The values of these constants are "North" , "South" , "East" ,
"West" , and "Center" . Although you can use a quoted string such as "North" as
the second argument to add , it is more consistent with our general style rules to use a
defined constant such as BorderLayout.NORTH .
You need not use all five regions. For example, in Display 17.7 we did not use the
regions BorderLayout.EAST and BorderLayout.WEST . If some regions are not used,
any extra space is given to the BorderLayout.CENTER region, which is the largest region.
(The space is divided between regions as follows: Regions are allocated space in the
order first north and south, second east and west, and last center. So, in particular, if
there is nothing in the north region, then the east and west regions will extend to the
top of the space.)