import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class MyPanel extends JPanel implements ActionListener {
	
	private JTextField readTf, writeTf;
	
	public MyPanel(){
		setSize(300, 300);
		setLayout(null);

		readTf = new JTextField("Type an integer here");
		readTf.setSize(200,40);
		readTf.setLocation(40,40);
		readTf.setEditable(true);
		readTf.addActionListener(this);

		add(readTf);

		writeTf = new JTextField();
		writeTf.setSize(200,40);
		writeTf.setLocation(40,120);
		writeTf.setEditable(false);
		add(writeTf);

		JButton jb = new JButton("Click here");
		jb.setSize(200,40);
		jb.setLocation(40,200);
		jb.addActionListener(this);
		add(jb);

		setVisible(true);
	}
	
	private int f (int x){
		return 2*x*x + 3*x +1;
	}

		public void actionPerformed(ActionEvent e){
			if(e.getSource() == readTf){
				String text = readTf.getText();
				int n = Integer.parseInt(text);
				writeTf.setText("" + f(n));
				readTf.setText("Type something here");
				}
			else writeTf.setText("No, hit return");
		}

}