My calculate button won't calculate - Please help

Hey JAVA Gods,

I was wondering if you folks can take a look see at the code below. I can't seem to get the calculate button to work....

/packages importedforclass and method use

import java.applet.Applet;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.event.*;

import javax.swing.text.*;

import java.awt.Button;

import java.awt.Graphics;

import java.awt.GridBagConstraints;

import java.awt.GridBagLayout;

import java.awt.Label;

import java.awt.TextField;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.text.NumberFormat;

publicclass MortageCalGUIextends JAppletimplements ActionListener{

TextField principalText, paymentText, termText, interestText;

Button calculate;//calculation button

double beginamount;// original principle

double intRate;// interest rate

double years;// length of loan in years

finalint numpayments = 12;//payments per year

NumberFormat format;

publicvoid init(){

// Use a grid bag layout.

GridBagLayout layout =new GridBagLayout();

GridBagConstraints constraints =new GridBagConstraints();

setLayout(layout);

Label heading =new Label("Tony's JAVA Applet Mortgage Calculator - POS407");

Label principalLabel =new Label("Principal(Loan Amount)");

Label termLabel =new Label("Number of Years");

Label interestLabel =new Label("The Interest Rate");

Label paymentLabel =new Label("Your Monthly Payment");

//Set field lengths

principalText =new TextField(10);

termText =new TextField(10);

paymentText =new TextField(10);

interestText =new TextField(10);

//Display payment field/not editable

paymentText.setEditable(false);

calculate =new Button("Calculate It");

// Define the grid bag

constraints.weighty = 1.0;//Distribute space of 1.0

constraints.gridwidth = GridBagConstraints.REMAINDER;//last component

constraints.anchor = GridBagConstraints.NORTH;//top of display/centered horizontally

layout.setConstraints(heading, constraints);

// Anchor most components to the right

constraints.anchor = GridBagConstraints.EAST;

//setting constraints

constraints.gridwidth = GridBagConstraints.RELATIVE;//place next to last component

layout.setConstraints(principalLabel, constraints);

constraints.gridwidth = GridBagConstraints.REMAINDER;

layout.setConstraints(principalText, constraints);

constraints.gridwidth = GridBagConstraints.RELATIVE;//place next to last component

layout.setConstraints(termLabel, constraints);

constraints.gridwidth = GridBagConstraints.REMAINDER;

layout.setConstraints(termText, constraints);

constraints.gridwidth = GridBagConstraints.RELATIVE;//place next to last component

layout.setConstraints(interestLabel, constraints);

constraints.gridwidth = GridBagConstraints.REMAINDER;

layout.setConstraints(interestText, constraints);

constraints.gridwidth = GridBagConstraints.RELATIVE;//place next to last component

layout.setConstraints(paymentLabel, constraints);

constraints.gridwidth = GridBagConstraints.REMAINDER;

layout.setConstraints(paymentText, constraints);

constraints.anchor = GridBagConstraints.CENTER;

layout.setConstraints(calculate, constraints);

// Add components

add(heading);

add(principalLabel);

add(principalText);

add(termLabel);

add(termText);

add(interestLabel);

add(interestText);

add(paymentLabel);

add(paymentText);

add(calculate);

// Receive action events

principalText.addActionListener(this);

termText.addActionListener(this);

interestText.addActionListener(this);

calculate.addActionListener(this);

// Number formatting

format = NumberFormat.getInstance();

format.setMinimumFractionDigits(2);

format.setMaximumFractionDigits(2);

}

//User presses calculate

publicvoid actionPerformed(ActionEvent calculate){

repaint();

}

// Displays result of calculations

publicvoid paint(Graphics g){

double result = 0.0;

String principalString = principalText.getText();

String termString = termText.getText();

String interestString = interestText.getText();

try{

if (principalString.length() != 0 && termString.length() != 0

&& interestString.length() != 0){

beginamount = Double.parseDouble(principalString);

years = Double.parseDouble(termString);

intRate = Double.parseDouble(interestString) / 100;

result = calculate();

principalText.setText(format.format(result));

}

showStatus("");// erase any error messages displayed

}catch (NumberFormatException exc){

showStatus("Invalid Input");

paymentText.setText("");

}

}

// Calculate the loan payment

double calculate(){

double first;

double second;

double x, z;

first = intRate * beginamount / numpayments;

x = -(numpayments * years);

z = (intRate / numpayments) + 1.0;

second = 1.0 - Math.pow(z,x);

return first / second;

}

}

[8816 byte] By [aguyfromgua] at [2007-11-27 11:33:36]