Creating Windows - Beginning Java - page 818

TRY IT OUT: Centering a Window

Here's the code:

import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public class TryWindow3 {
public static void createWindow(){
JFrame aWindow = new JFrame("This is the Window Title");
int windowWidth = 400; // Window width

in pixels
int windowHeight = 150; // Window height

in pixels
aWindow.setSize(windowWidth, windowHeight); // Set window

size

aWindow.setLocationRelativeTo(null); // Center window

aWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
aWindow.setVisible(true); // Display the

window
}

public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createWindow();

}

});

}

}

TryWindow3.java

When you execute this, you should see the window displayed centered on your primary display.
How It Works
This example calls the setSize() method for aWindow to specify the dimension for the window. Calling
setLocationRelativeTo() with a null argument centers the window relative to the primary monitor.

Points and Rectangles
Before continuing with the Component class methods, let's digress briefly into more detail concerning the
Point and Rectangle classes, as they are going to come up quite often. As you've seen, both these classes
are defined in java.awt . You will find many of the methods provided by the Point and Rectangle classes
very useful when drawing in a window. Entities displayed in a window typically have Rectangle objects