do

vimport javax.swing.*;

import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.util.*;

public class WindowApplication extends JFrame implements ActionListener{
	private JTextField textField;
	private JFrame frame;//
	private JButton button;

	public WindowApplication() {
		setSize(320 , 240);
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		setBackground(Color.BLACK);

		button = new JButton("Change title");
		button.addActionListener(this);

		textField = new JTextField(20);
		getContentPane().add(textField);
		getContentPane().add(button);
	}

	@Override
	public void actionPerformed(ActionEvent arg0) {
		String text = textField.getText();
		setTitle(text);
	}

	public static void main(String[] args) {
		Work work = new Work();
		Thread t = new Thread(work);
		t.start();
	}
}

class Work implements Runnable{
	@Override
	public void run() {
		new WindowApplication().setVisible(true);
	}
}