Editing Swing (Java) (section)

===Window with Button===
[[File:Swing example on Windows 7.png|thumb|right|The basic example code running on [[Windows 7]]]]

The following is a rather simple Swing-based program. It displays a window (a {{Javadoc|module=java.desktop|package=javax.swing|class=JFrame|text=JFrame|monotype=y}}) containing a label and a button.

<syntaxhighlight lang="java">
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.WindowConstants;
import javax.swing.SwingUtilities;
 
public class SwingExample implements Runnable {
    private JFrame f;
    public SwingExample()  {
        // Create the window
        f = new JFrame("Hello World!");
        // Sets the behavior for when the window is closed
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        // Add a layout manager so that the button is not placed on top of the label
        f.setLayout(new FlowLayout());
        // Add a label and a button
        f.add(new JLabel("Hello, world!"));
        f.add(new JButton("Press me!"));   
    }

    @Override
    public void run() {
        // Arrange the components inside the window
        f.pack();
        // By default, the window is not visible. Make it visible.
        f.setVisible(true);
    }
 
    public static void main(String[] args) {
        // Schedules the application to be run at the correct time in the event queue.
        SwingUtilities.invokeLater(new SwingExample());
    }

}
</syntaxhighlight>
Notice how all instantiation and handling of Swing components are done by creating an instance of the class, 
which implements the Runnable interface. This is then run on the [[Event Dispatch Thread]] by use of the method {{Javadoc:SE|member=invokeLater(Runnable)|javax/swing|SwingUtilities|invokeLater(java.lang.Runnable)|module=java.desktop}}), created in the main method (see [[Event dispatching thread#Swing and thread safety|Swing and thread safety]]). Although Swing code can be run without using this technique (for instance, by not implementing Runnable and moving all commands from the run method to the main method), it is considered to be good form, as Swing is not [[Thread safety|thread-safe]], meaning that invoking resources from multiple threads can result in thread interference and memory consistency errors.<ref>{{Cite web|url=https://docs.oracle.com/javase/tutorial/uiswing/concurrency/dispatch.html|title=The Event Dispatch Thread|website=docs.oracle.com}}</ref>