//<PLAINTEXT>
package SwingDemos;

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

/**
 * CalculatorPanel.java
 *
 *
 * Created: Tue Mar 18 11:22:33 2003
 *
 * @author <a href="mailto:shapiro@cse.buffalo.edu">Stuart C. Shapiro</a>
 * @version
 */

public class CalculatorPanel extends JPanel implements ActionListener {
    JTextField op1, op2;
    JLabel results;
    JButton quitButton;

    public CalculatorPanel (){
	setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
	JPanel fieldPanel = new JPanel();

	op1 = new JTextField("0",5);
	op2 = new JTextField("0",5);
	results = new JLabel("0");
	quitButton = new JButton("Quit");

	op1.addActionListener(this);
	op2.addActionListener(this);
	quitButton.addActionListener(this);

	fieldPanel.add(op1);
	fieldPanel.add(new JLabel(" x "));
	fieldPanel.add(op2);
	fieldPanel.add(new JLabel(" = "));
	fieldPanel.add(results);

	add(fieldPanel);
	add(quitButton);
    }
    
    public void actionPerformed(ActionEvent evt) {
	if (evt.getSource() == quitButton) {
	    System.exit(0);
	} else {
	    try {results.setText("" +
				Integer.parseInt(op1.getText())
				* Integer.parseInt(op2.getText()));
	    } catch (NumberFormatException e) {
		 JOptionPane.showMessageDialog(this,
					       "The entry must be an integer.",
					       "error",
					       JOptionPane.ERROR_MESSAGE);
	    } // end of try-catch
	} // end of if-else
    } // actionPerformed

}// CalculatorPanel