OnJava8-Examples/ui/HelloSwing.java

// ui/HelloSwing.java
import javax.swing.*;

public class HelloSwing {
  public static void main(String[] args) {
    JFrame frame = new JFrame("Hello Swing");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 100);
    frame.setVisible(true);
  }
}