Editing Swing (Java) (section)

===Another example===
In this example let javax.swing.JFrame be super class and add our own widget(s) to it (in this case, a JButton).

<syntaxhighlight lang="java">
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class Sample extends JFrame {
	private final JButton b = new JButton();

	public Sample() {
		super();
		this.setTitle("HelloApp");
		this.getContentPane().setLayout(null);
		this.setBounds(100, 100, 180, 140);
		this.add(makeButton());
		this.setVisible(true);
		this.setDefaultCloseOperation(EXIT_ON_CLOSE);
	}

	private JButton makeButton() {
		b.setText("Click me!");
		b.setBounds(40, 40, 100, 30);
		b.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				JOptionPane.showMessageDialog(b, "Hello World!");
			}
		});
		return b;
	}

	public static void main(String[] args) throws InvocationTargetException, InterruptedException {
		// Swing calls must be run by the event dispatching thread.
		SwingUtilities.invokeAndWait(() -> new Sample());
	}
}
</syntaxhighlight>
The layout is set to null using the {{Javadoc:SE|member=setLayout(LayoutManager)|java/awt|Container|setLayout(java.awt.LayoutManager)|module=java.desktop}} method since JFrame uses java.awt.BorderLayout as its default layout-manager. With BorderLayout anything which is added to the container is placed in the center and stretched to accommodate any other widgets. Of course, most real world GUI applications would prefer to use a layout-manager instead of placing everything on absolute co-ordinates.<ref>{{cite book|last1=Eckel|first1=Bruce|title=Thinking in Java|date=2006|publisher=Prentice Hall|isbn=978-0131872486|page=942|edition=4|url=http://www.agentgroup.unimore.it/~nicola/courses/IngegneriaDelSoftware/java/books/ThinkingInJava.pdf|access-date=13 May 2016|url-status=dead|archive-url=https://web.archive.org/web/20160514000820/http://www.agentgroup.unimore.it/~nicola/courses/IngegneriaDelSoftware/java/books/ThinkingInJava.pdf|archive-date=14 May 2016}}</ref>