Mortgage Calc - URGENT Help

I am a student and was asked to write a mortgage calculator program using the GUI. I wrote it but it is giving me an error. I spent some time to debug it but I am not able to determine what's causing the problem.
Can you plese help to resolve my problem?

.java and . form are in the below directory.

Ok, I have gotten rid of the arrayIndex exception, I've moved some
variables up to class-level and fixed the logics in jButton1ActionPerformed.
I also put in a numeric validity check. I've had to replace your layout
with an XY-layout to make it compile on my system.

I noticed that you haven't added the radiobuttons to the buttongroup, but
I didn't do anything about it, since it seems to be within the realms of
your development tools auto generated code.

Btw, except for a thankyou, you owe me nada :)

Code:

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/*
 * Ozdinc_Week_3.java
 *
 * Created on May 29, 2005, 2:53 AM
 */
import java.lang.*;
import java.math.*;
import java.text.*;
import java.awt.*;
import javax.swing.*;
import com.borland.jbcl.layout.*;

/* @author  Chad Ozdinc
 */
public class Ozdinc_Week_3  extends JFrame {

  // Decimal format

    static DecimalFormat decmat = new DecimalFormat("$#,##0.00");

    static double[] rate = new double[] {
        .0535, .055, .0575};
    static int[] term = new int[] {
        7, 15, 30};



  /** Creates new form Ozdinc_Week_3 */
  public Ozdinc_Week_3() {
    jbInit();
    setSize(575, 575);
    this.setTitle("POS/407 Chad's Mortgage Calculator");
  }

  /** This method is called from within the constructor to
  * initialize the form.
  * WARNING: Do NOT modify this code. The content of this method is
  * always regenerated by the Form Editor.
  */
  private void jbInit() { //GEN-BEGIN:initComponents
    buttonGroup1 = new javax.swing.ButtonGroup();
    Amount = new javax.swing.JTextField();
    jTextPane1 = new javax.swing.JTextPane();
    term1 = new javax.swing.JRadioButton();
    term2 = new javax.swing.JRadioButton();
    term3 = new javax.swing.JRadioButton();
    jButton1 = new javax.swing.JButton();
    jScrollPane3 = new javax.swing.JScrollPane();
    textOut = new javax.swing.JTextArea();
    monthlyPay = new javax.swing.JLabel();
    jLabel3 = new javax.swing.JLabel();
    btnClear = new javax.swing.JButton();
    jMenuBar1 = new javax.swing.JMenuBar();
    jMenu1 = new javax.swing.JMenu();

    getContentPane().setLayout(xYLayout1);

    setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    xYLayout1.setWidth(553);
    xYLayout1.setHeight(398);
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(30, 50, 130, -1));

    jTextPane1.setBackground(new java.awt.Color(212, 208, 200));
    jTextPane1.setText("Loan Amount");
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(30, 20, 80, -1));

    term1.setText("7 years at 5.35%");
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(30, 100, 120, -1));

    term2.setText("15 years at 5.5%");
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(360, 100, 110, -1));

    term3.setText("30 years at 5.75%");
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(200, 100, 130, -1));

    jButton1.setText("Calculate");
    jButton1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        jButton1ActionPerformed(evt);
      }
    });

                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(240, 50, -1, -1));

    jScrollPane3.setHorizontalScrollBarPolicy(javax.swing.JScrollPane.
                                              HORIZONTAL_SCROLLBAR_ALWAYS);
    jScrollPane3.setVerticalScrollBarPolicy(javax.swing.JScrollPane.
                                            VERTICAL_SCROLLBAR_ALWAYS);

                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(0, 170, 510, 100));

                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(180, 130, 280, 20));

    jLabel3.setText("Your monthly payment is:");
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(10, 140, 130, -1));

    btnClear.setText("Clear All");
    btnClear.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        btnClearActionPerformed(evt);
      }
    });

    monthlyPay.setBorder(BorderFactory.createEtchedBorder());
    monthlyPay.setHorizontalAlignment(SwingConstants.RIGHT);
    this.getContentPane().add(jScrollPane3,  new XYConstraints(48, 221, 303, 83));
    this.getContentPane().add(btnClear,  new XYConstraints(48, 317, 187, 27));
    this.getContentPane().add(jLabel3,      new XYConstraints(50, 185, 145, 25));
    this.getContentPane().add(jButton1, new XYConstraints(48, 151, 147, 27));
    this.getContentPane().add(term3, new XYConstraints(52, 115, -1, 27));
    this.getContentPane().add(term1, new XYConstraints(52, 64, 123, 27));
    this.getContentPane().add(term2, new XYConstraints(52, 90, 123, 27));
    this.getContentPane().add(jTextPane1,  new XYConstraints(44, 24, 99, 24));
    this.getContentPane().add(Amount, new XYConstraints(146, 25, 179, 24));
    this.getContentPane().add(monthlyPay,    new XYConstraints(212, 185, 139, 25));
    jScrollPane3.setViewportView(textOut);
                        //new org.netbeans.lib.awtextra.
                        //AbsoluteConstraints(230, 280, -1, -1));

    jMenu1.setText("Menu");
    jMenu1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
        jMenu1ActionPerformed(evt);
      }
    });

    jMenuBar1.add(jMenu1);

    setJMenuBar(jMenuBar1);

    pack();
  } //GEN-END:initComponents

  private void btnClearActionPerformed(java.awt.event.ActionEvent evt) { //GEN-FIRST:event_btnClearActionPerformed
    // Clear Button:

    Amount.setText("");
    textOut.setText("");

  } //GEN-LAST:event_btnClearActionPerformed

  private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { //GEN-FIRST:event_jButton1ActionPerformed

    double beginingAmount = 0.0;
    try {
      beginingAmount = Double.parseDouble(Amount.getText().trim());
    }
    catch (NumberFormatException ex) {
      JOptionPane.showMessageDialog(this,"Invalid numeric input","User error",
                                    JOptionPane.ERROR_MESSAGE);
      return;
    }

    int number = 0;

    if (term1.isSelected()) {
      number = 0;
    } else if (term2.isSelected()) {
      number = 1;
    } else if (term3.isSelected()) {
      number = 2;
    }

    double payment = (beginingAmount * rate[number]) /
        (1.0d - Math.pow(1.0d / (1.0d + rate[number] / 12.0d), term[number] * 12.0d)) /
        12.0d;



    monthlyPay.setText(decmat.format(payment));
    double payPri = 0;
    int months = 1;
    while (months <= term[number] * 12) {

      double intrest1 = ( (rate[number] * beginingAmount) / 12.0d);
      payPri = payment - intrest1;
      beginingAmount = (beginingAmount - payPri);
      textOut.append(months + "\t" + decmat.format(intrest1) + "\t" +
                    decmat.format(beginingAmount) + "\n");
      months++;

    }
  } //GEN-LAST:event_jButton1ActionPerformed

  private void jMenu1ActionPerformed(java.awt.event.ActionEvent evt) { //GEN-FIRST:event_jMenu1ActionPerformed

    // TODO add your handling code here:

    this.dispose();
  } //GEN-LAST:event_jMenu1ActionPerformed

  /**
  * @param args the command line arguments
  */
  public static void main(String args[]) {
    java.awt.EventQueue.invokeLater(new Runnable() {
      public void run() {
        new Ozdinc_Week_3().setVisible(true);
      }
    });
  }

  // Variables declaration - do not modify//GEN-BEGIN:variables
  private javax.swing.JTextField Amount;
  private javax.swing.JButton btnClear;
  private javax.swing.ButtonGroup buttonGroup1;
  private javax.swing.JButton jButton1;
  private javax.swing.JLabel jLabel3;
  private javax.swing.JMenu jMenu1;
  private javax.swing.JMenuBar jMenuBar1;
  private javax.swing.JScrollPane jScrollPane3;
  private javax.swing.JTextPane jTextPane1;
  private javax.swing.JLabel monthlyPay;
  private javax.swing.JRadioButton term1;
  private javax.swing.JRadioButton term2;
  private javax.swing.JRadioButton term3;
  private javax.swing.JTextArea textOut;
  XYLayout xYLayout1 = new XYLayout();
  // End of variables declaration//GEN-END:variables

}

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