[hardwired]

Code:

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

public class TimesRx /*extends JFrame*/ implements ActionListener
{
    private JTextArea txtTable;
    private JLabel enterNumber;
    private JButton calc, reset;
    private JTextField numberText;
    private int number;
    private int times=1;

    // You do not need to extend JFrame if you are
    // going to create a new instance like this.
    JFrame wind = new JFrame("Times Table");

    public TimesRx()
    {
        //Set the window's bounds, centring the window
        Toolkit myKit = wind.getToolkit();
        int width=250; //sets the JFrame width
        int height=400; //sets the JFrame height
        //gets the screen size currently being used by user
        Dimension wndSize = myKit.getScreenSize();
        //calculates the x and y coordinates for the JFrame
        int x = (wndSize.width - width) / 2;
        int y = (wndSize.height - height) / 2;
        //sets the coordinates and size of the JFrame
        wind.setBounds(x,y,width,height);
        // Another option to the above centering code:
        // wind.setLocationRelativeTo(null);
        //sets default close operation
        wind.setDefaultCloseOperation(//EXIT_ON_CLOSE);
                                      JFrame.EXIT_ON_CLOSE);

        wind.setResizable(false);
        //builds the container
        Container c = wind.getContentPane();
        //sets containers background colour
        c.setBackground(Color.pink);
        //sets containers layout
        c.setLayout(new FlowLayout());
        //creates the new JLabel
        enterNumber = new JLabel("Enter Number between 1 " + "and 20");
        //adds the JLabel to the container
        c.add(enterNumber);
        //creates new JTextField
        numberText = new JTextField(3);

        numberText.setBackground(Color.pink);
        //adds the JTextField to container
        c.add(numberText);
        //creates new JButton
        calc = new JButton("Calculate");

        calc.setBackground(Color.pink);
        //adds the new JButton to the container
        c.add(calc);
        //adds an ActionListener to the JButton
        calc.addActionListener(this);
        //creates new JButton
        reset = new JButton("Reset");

        reset.setBackground(Color.pink);
        //adds the new JButton to the container
        c.add(reset);
        //adds an ActionListener to the JButton
        reset.addActionListener(this);
        //creates a new JTextArea 
        txtTable = new JTextArea(13, 10);
        txtTable.setBackground(Color.pink);
        txtTable.setFont(new Font(//"Papyrus",Font.PLAIN,14));
                                  "Monospaced", Font.PLAIN,14));

        txtTable.setEditable(false);

        txtTable.setBorder(BorderFactory.createLineBorder( Color.black));
        //adds the new JTextArea to the container
        c.add(txtTable);
        //this sets the JFrame to be visible
        wind.setVisible(true);
    }

    public static void main(String[] args)
    {
        //creates a new "times()"
        TimesRx myTimes = new TimesRx();
    }

    public void actionPerformed(ActionEvent arg0)
    {
        //a try/catch statement
        try
        {
            //an if statement, what the calc JButton does
            if (arg0.getSource() == calc)
            {
                //local variable
                int total;
                /*when calc button pressed, "number" = the text
                 * inside the "numberText" JTextField, and then
                 * must be an integer to be "number" */
                number = Integer.parseInt(numberText.getText());
                /*if there is already 12 lines in the JTextArea,
                 * then a error message comes up */
                if(times>=12)
                   error("Please hit reset and try again");
                /*If a number below 1, or higher than 20 is entered
                 * into the JTextField, then an error message will
                 * come up */
                if(number<1||number>20)
                    error("Number out of range!!");

                /* If "number" passes the last "If" statements,
                 * then it will passed down to the "else" statement */
                else
                {
                    // a while loop
                    while (times <= 12)
                    {
                        //calculation for the total
                        total = number * times;
                        // this inputs text to the JTextArea
                        // String.format was introduced in j2se 1.5
                        String s = String.format("%2s x %2d = %3d%n",
                                                  times, number, total);
                        System.out.print(s);
                        txtTable.append(s);
//                        txtTable.append(" " + times + " x " + number + 
//                                        " = " + total + "\n");
                        //times = times + 1
                        times++;
                    }
                }
                // The JTextField is set to nothing
                numberText.setText("");
                // The cursor is put in the JTextField
                numberText.requestFocus();
            }
            //An "if" statement for the reset button
            if (arg0.getSource() == reset)
            {
                //sets the JTextArea to nothing
                txtTable.setText("");
                //sets the JTextField to nothing
                numberText.setText("");
                //the cursor is put in the JTextField
                numberText.requestFocus();
                //times is set back to 1
                times=1;
            }
        }
        /*if the "numberText couldn't be converted to a integer
         * for "number" at the beginning of the "try/catch" statement,
         * then it misses out the rest and is thrown to the "catch",
         * which will come up with an error message */
        catch(NumberFormatException e)
        {
            error("Invalid character, please try again");
        }
    }

    //the error method
    private void error(String message)
    {
        //dialog box comes up with a message
        JOptionPane.showMessageDialog(null,message);
        //the JTextField is set to nothing
        numberText.setText("");
        //the cursor is put in the JTextField
        numberText.requestFocus();
    }
}