import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import java.awt.BorderLayout;
import java.awt.GridLayout;

public class SwingExample extends JFrame implements Runnable
{   
    public SwingExample()
    {   
        //initalize any state here.
        super("Swing Example");
    }
    public void run()
    {   
        
        setSize(500,400);
        getContentPane().setLayout(new BorderLayout());
        JButton b = new JButton("Clear!");
        JTextArea jta = new JTextArea();
        b.addActionListener( e -> jta.setText(""));
        getContentPane().add(BorderLayout.NORTH, b);
        getContentPane().add(BorderLayout.CENTER, jta);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }
    public static void main(String[] args)
    {
        //don't modify this other than changing the
        //class name in the first line. It ensures
        //thread sanity.
        SwingExample c = new SwingExample();
        javax.swing.SwingUtilities.invokeLater(c);
    }
   
}