Swing sample

SwingTest.java

import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

class SwingTest {
  public static void main(String args[]) {
    JFrame window = new JFrame("title");
    JButton button = new JButton("button");
    button.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent ae) {
        System.out.println("button clicked");
      }
    });
    window.add(button);
    window.setLocationRelativeTo(null);
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.setSize(160, 160);
    window.setVisible(true);
  }
}