Winston Tutorial 11 & 12 Mouse Mover

package com.samkough.main;

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

@SuppressWarnings("serial")
public class Win extends JFrame implements ActionListener
{
	// private static final int WIDTH = 300;
	// private static final int HEIGHT = 300;

	JLabel l1, l2, l3, l4, errorLabel;
	JTextField tf1, tf2, tf3, tf4;
	JButton b1;

	public Win()
	{
		// rows, columns, then the last two are for padding
		// horizontal padding and vertical padding
		setLayout(new GridLayout(5, 2, 5, 5));

		l1 = new JLabel("Enter number of movements:");
		l2 = new JLabel("Enter delay between movements milliseconds:");
		l3 = new JLabel("Enter screen width in pixels:");
		l4 = new JLabel("Enter screen height in pixels:");
		errorLabel = new JLabel("");
		tf1 = new JTextField();
		tf2 = new JTextField();
		tf3 = new JTextField();
		tf4 = new JTextField();
		b1 = new JButton("Start!");

		add(l1);
		add(tf1);
		add(l2);
		add(tf2);
		add(l3);
		add(tf3);
		add(l4);
		add(tf4);
		add(b1);
		add(errorLabel);

		b1.addActionListener(this);
	}

	public void actionPerformed(ActionEvent e)
	{
		try
		{
			int num = (int)(Double.parseDouble(tf1.getText()));
			int delay = (int)(Double.parseDouble(tf2.getText()));
			int width = (int)(Double.parseDouble(tf3.getText()));
			int height = (int)(Double.parseDouble(tf1.getText()));

			if (num <= 0 || delay <= 0 || width <= 0 || height <= 0)
			{
				errorLabel.setText("Please enter positive values only.");
			}
			else
			{
				errorLabel.setText("");

				try
				{
					Robot rob = new Robot();
					for (int x = 0; x <= num; x++)
					{
						// what this is gonna do is move the mouse in random directions around the screen
						rob.mouseMove((int)(Math.random() * width), (int)(Math.random() * height));
						rob.delay(delay);
					}
				}
				catch(AWTException ex)
				{
					System.exit(0);
				}
			}
		}
		catch(Exception exx)
		{
			errorLabel.setText("Numbers only and no blank spaces!");
		}
	}

	public static void main(String args[])
	{
		Win frame = new Win();

		frame.setVisible(true);
		// frame.setSize(WIDTH, HEIGHT);
		frame.pack();
		frame.setTitle("Mouse Mover");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLocationRelativeTo(null);
	}
}