import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Main02{

public static void main(String args[]){

new AppFrame();

}

}

class AppFrame extends JFrame{

JTextField in = new JTextField();

JButton btn = new JButton("evaluate x square");

JLabel out = new JLabel("label for showing the result");

public AppFrame(){

setLayout(new FlowLayout());

getContentPane().add(in);

getContentPane().add(btn);

getContentPane().add(out);

btn.addActionListener(new BtnActionAdapter());

// btn.setSize(200, 50);

setSize(400,100);

setDefaultCloseOperation(DISPOSE_ON_CLOSE);

setVisible(true);

}

class BtnActionAdapter implements ActionListener{

public void actionPerformed(ActionEvent e){

String s = in.getText();

double d = Double.parseDouble(s);

out.setText("square is: " + d*d);

}

}

}