Java tutorial
import java.awt.Container; import javax.swing.JButton; import javax.swing.JFrame; public class Main { public static void main(String[] args) { JFrame frame = new JFrame("JFrame"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Add a close button JButton closeButton = new JButton("Close"); Container contentPane = frame.getContentPane(); contentPane.add(closeButton); // Calculates and sets appropriate size for the frame frame.pack(); frame.setVisible(true); } }