BorderLayout

Applets use a default layout scheme: the BorderLayout (a number of the previous examples have changed the layout manager to FlowLayout). Without any other instruction, this takes whatever you add( ) to it and places it in the center, stretching the object all the way out to the edges.

However, there’s more to the BorderLayout. This layout manager has the concept of four border regions and a center area. When you add something to a panel that’s using a BorderLayout, you can use the overloaded add( ) method that takes a constant value as its first argument. This value can be any of the following:

If you don’t specify an area to place the object, it defaults to CENTER.

Here’s a simple example. The default layout is used, since JApplet defaults to BorderLayout:

//: c14:BorderLayout1.java
// Demonstrates BorderLayout.
//<applet code=BorderLayout1 width=300 height=250></applet>
import javax.swing.*;
import java.awt.*;
import com.bruceeckel.swing.*;

public class BorderLayout1 extends JApplet {
  public void init() {
    Container cp = getContentPane();
    cp.add(BorderLayout.NORTH, new JButton("North"));
    cp.add(BorderLayout.SOUTH, new JButton("South"));
    cp.add(BorderLayout.EAST, new JButton("East"));
    cp.add(BorderLayout.WEST, new JButton("West"));
    cp.add(BorderLayout.CENTER, new JButton("Center"));
  }
  public static void main(String[] args) {
    Console.run(new BorderLayout1(), 300, 250);
  }
} ///:~

For every placement but CENTER, the element that you add is compressed to fit in the smallest amount of space along one dimension while it is stretched to the maximum along the other dimension. CENTER, however, spreads out in both dimensions to occupy the middle.

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