import javax.swing.*;
import java.text.DecimalFormat;


/**
 *
 * @author rgilbert
 */
public class Main
{
    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI()
    {

        // Declare variables
        int n;
        float sum = 0.0f;
        float mysqrt = 0.0f;
        String sOutput = "";

        // Decimal Format.
        DecimalFormat formatter = new DecimalFormat("#0.0000");

        // Loop
        for( n=1; n <= 999 ;n++ )
        {
            mysqrt = (float) Math.sqrt((float) n);
            sum += mysqrt;

            sOutput += formatter.format(mysqrt);

            if ( n % 3 == 0 )
            {
                sOutput += "\t" + formatter.format(sum) + "\n";
                sum = 0.0f;
            }
            else
            {
                sOutput += "\t";
            }

        }

        //Create and set up the window.
        JFrame frame = new JFrame("Loop Exercise");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextArea area = new JTextArea(sOutput, 30, 50);
        JScrollPane scroll = new JScrollPane(area);
        frame.getContentPane().add(scroll);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                createAndShowGUI();
            }
        });
    }

}