I need to modify the following code/GUI so that not only does it calculate the volume of a swimming pool, but it tells how much water is needed and how much is costs to fill up the pool if water is .77 cents per cubic foot with a one time cost of $100.00. I just cant figure out how to make the program do those extra calculations. Thanks.

import java.io.*;
import java.text.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.text.DecimalFormat;

public class PoolVolume {
private JFrame mainFrame;
private JButton calcButton, exitButton;
private JTextField length, width, depth, volume;
private JLabel lengthLabel, widthLabel, depthLabel, volumeLabel;
public PoolVolume() {
mainFrame = new JFrame("Swimming Pool Volume Calculator");
calcButton = new JButton("Calculate volume");
exitButton = new JButton("Exit");
length = new JTextField(5);
width = new JTextField(5);
depth = new JTextField(5);
volume = new JTextField(5);
lengthLabel = new JLabel("Enter the length of the swimming pool: ");
widthLabel = new JLabel("Enter the width of the swimming pool: ");
depthLabel = new JLabel("Enter the depth dept of the swimming pool: ");
volumeLabel = new JLabel("Swimming pool volume: ");
JPanel c=new JPanel(new GridLayout(5,2));
c.add(lengthLabel);
c.add(length);
c.add(widthLabel);
c.add(width);
c.add(depthLabel);
c.add(depth);
c.add(volumeLabel);
c.add(volume);
c.add(calcButton);
c.add(exitButton);
calcButton.setMnemonic('C');
exitButton.setMnemonic('x');
mainFrame.setSize(500,200);
mainFrame.add(c);
mainFrame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}});
calcButtonHandler chandler =new calcButtonHandler();
calcButton.addActionListener(chandler);
exitButtonHandler ehandler =new exitButtonHandler();
exitButton.addActionListener(ehandler);
FocusHandler fhandler =new FocusHandler();
length.addFocusListener(fhandler);
width.addFocusListener(fhandler);
depth.addFocusListener(fhandler);
volume.addFocusListener(fhandler);
mainFrame.setVisible(true);
}
class calcButtonHandler implements ActionListener {
public void actionPerformed(ActionEvent e) {
DecimalFormat num =new DecimalFormat(",###.##");
Double cLength, cWidth, cdepth, cVolume, Total;
String sLength, sWidth, sdepth, sVolume;
sLength =length.getText();
cLength = Double.parseDouble(sLength);
sWidth =width.getText();
cWidth = Double.parseDouble(sWidth);
sdepth =depth.getText();
cdepth = Double.parseDouble(sdepth);
if(e.getSource() == calcButton) {
Total = cLength * cWidth * cdepth;
volume.setText(num.format(Total));
try{
String value=volume.getText();
File file = new File("output.txt");
FileWriter fstream = new FileWriter(file,true);
BufferedWriter out = new BufferedWriter(fstream);
out.write("Length= "+sLength+", Width= "+sWidth+", Depth= "+sdepth+" so the volume of Swimming Pool is "+value);
out.newLine();
out.close();
}
catch(Exception ex){}
}
}
}
class exitButtonHandler implements ActionListener {
public void actionPerformed(ActionEvent e){
System.exit(0);
}
}
class FocusHandler implements FocusListener {
public void focusGained(FocusEvent e) {
}
public void focusLost(FocusEvent e) {
}
}
public static void main(String args[]){
new PoolVolume();
}
}