Need a little help with a Jbutton not working out the way I planned

Question

The following code is to fulfill an assignment I am working on. The problem I am having is with the btnCalc. For some reason when the button is used, the results I get is from another button. I think the variables are set right for the program to function properly but I am really hung up on this. Do anyone have any suggestions?
import java.awt.*;                     //Contains classes for creating GUI
import java.awt.event.*;                //For listener events
import javax.swing.*;                     // Imports the Main Swing Package
import javax.swing.event.*;
import javax.swing.text.*;           // Positions text box
import java.text.NumberFormat;          // For number format such as currency
import java.text.*;                     // Imports the Main Text Package
import java.util.*;                     // Utility Package
public class MPC extends JFrame implements ActionListener           //Creates Class for MPC
//double dblLoanAmount, dblInterestRate, dblMonthlyPayment;
TextField txtTotalMort;
     //JButton fixRates = new JButton("Choose Fixed Rates");
     JLabel lblTotalMort = new JLabel("How much is the loan?"); // Label for dblLoanAmount amount
     JTextField txtYears = new JTextField(10);
     JLabel lblPayment = new JLabel("Your monthly payment is "); // Label for Payment
     JTextField txtPayment = new JTextField(10);
     JLabel lblYears = new JLabel("How many years?");
                         // add(lblYears);
               JTextField txtYearsInput = new JTextField(10);
                         //a dd(txtYears);
     JLabel lblInterestRate = new JLabel("What is the interest rate?");
                         //add(lblInterestRate);
               JTextField txtInterestRate = new JTextField(10);
                         //add(txtInterestRate);
     //JLabel lblPayment = new JLabel("Your monthly payment is:");
                         //add(lblPayment);
               //JTextField txtPayment = new JTextField(10);
                         //txtPayment.setEditable(false);
                              //add(txtPayment);
     JButton btnCalc = new JButton("Calculate");
                         //add(btnCalc);
                         //btnCalc.addActionListener(this);
JButton year7InterestRateBtn = new JButton("7 years at 5.35%");     // Mortgage Term and Interest Rate
JButton year15InterestRateBtn = new JButton("15 years at 5.50%");
JButton year30InterestRateBtn = new JButton("30 years at 5.75%");
JButton reset = new JButton("Clear All");
JTextArea boxSpace = new JTextArea(100,200);          // Morgtage table size
JScrollPane scroll = new JScrollPane(boxSpace);     // ScrollPane
          public MPC()     // Method
     super("MPC");     // Frame Title
          JMenuBar mb = new JMenuBar();     // Menu Bar
setJMenuBar(mb);
                    setSize(325, 500);          // Frame Size
                    JPanel pane = new JPanel();
                    pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS)); //Grid box configuration
                    Container grid = getContentPane();
                    grid.setLayout(new GridLayout(8,2,8,8));     // Grid Layout
                    pane.add(grid);                                        // Adds grid
                    pane.add(scroll);                                   // Adds scrollPane
               grid.setBackground(Color.white);
                    Setting color of text and backgrounds
               txtYears.setBackground(Color.white);
          txtYears.setForeground(Color.black);
               txtYears.setFont(new Font("Arial", Font.PLAIN, 10));
                    txtPayment.setBackground(Color.white);
               txtPayment.setForeground(Color.black);
          txtPayment.setFont(new Font("Arial", Font.PLAIN, 10));
               boxSpace.setBackground(Color.white);
               boxSpace.setForeground(Color.black);
               boxSpace.setFont(new Font("Arial", Font.PLAIN, 10));
          grid.add(lblYears);
          grid.add(txtYearsInput);
          grid.add(lblInterestRate);
          grid.add (txtInterestRate);
          grid.add(lblTotalMort);          // Adds the Mortgage Amount Label
          grid.add(txtYears);               // Adds the Mortgage Amount Text Field
          grid.add(lblPayment);           // Adds the Payment Label
          grid.add(txtPayment);           // Adds the Monthly Payment Text Field
               txtPayment.setEditable(false);          // Disables editing in this Text Field
          grid.add(btnCalc);
     grid.add(year7InterestRateBtn);               // Adds 1st Loan and Rate Button
          grid.add(year15InterestRateBtn);          // Adds 2nd Loan and Rate Button
          grid.add(year30InterestRateBtn);          // Adds the Exit Button
          grid.add(reset);                               // Adds the New Calc Button
          setContentPane(pane);                          // Enables the Content Pane
          setVisible(true);                               // Sets JPanel to be Visable
          reset.addActionListener(this);                          // Adds Action Listener to the New Calc Button
          txtYearsInput.addActionListener(this);
          txtInterestRate.addActionListener(this);
          btnCalc.addActionListener(this);
     year7InterestRateBtn.addActionListener(this);                              // Adds Action Listener to the 1st loan Button
          year15InterestRateBtn.addActionListener(this);                              // Adds Action Listener to the 2nd loan Button
          year30InterestRateBtn.addActionListener(this);                               // Adds Action Listener to the 3rd loan Button
          txtYears.addActionListener(this);                              // Adds Action Listener to the Mortgage Amount Text Field
          txtPayment.addActionListener(this);                              // Adds Action Listener to the Monthly payment Text Field
          public void actionPerformed(ActionEvent e)                               // Tests to Verify Which Button is Pressed
     Object command = e.getSource(); // Enables command to get data
     int intYears = 0;          // Declares intYears
               double dblLoanAmount, dblInterestRate, interestRate, intRate;
     if (command == year7InterestRateBtn)                                   // Activates the 1st Loan Button
intYears = 0;                                        // Sets 1st value of Array
     if (command == year15InterestRateBtn)                                   // Activates the 2nd Loan Button
     intYears = 1;                                        // Sets 2nd value of Array
          if (command == year30InterestRateBtn)                                   // Activates the 3rd Loan Button
               intYears = 2;                                        // Sets 3rd value of Array
               if (command == btnCalc)
                    //dblLoanAmount = Double.parseDouble(txtTotalMort.getText() ); // Loan amount
                    //interestRate = Double.parseDouble(txtInterestRate.getText() ); // /100 )/ 12; // Devides rate
                    intRate = (Double.parseDouble(txtInterestRate.getText() )/100 )/ 12;
                    //int intYearsMonths = Integer.parseInt(txtYearsInput.getText() );// * 12; //Multiplies loan length
                    int months = Integer.parseInt(txtYearsInput.getText() )* 12;
dblLoanAmount = 0;                                   // Declares and Initializes dblLoanAmount
               dblInterestRate = 0;                                        // Declares and Initializes dblInterestRate
          double [][] dblTrmLoanRate = {{7, 5.35}, {15, 5.50}, {30, 5.75},};           // Array Data for Calculation
try
dblLoanAmount = Double.parseDouble(txtYears.getText()); // Gets user input from txtYears Text Field
catch (NumberFormatException nfe)                          // Checks for correct user input
                         JOptionPane.showMessageDialog(null, "You must enter a valid number.", "MPC", JOptionPane.INFORMATION_MESSAGE);
return;
          interestRate = dblTrmLoanRate [intYears][1];
               //dblInterestRate=interestRate;
               intRate = (interestRate / 100) / 12;                         // Calculates Interst Rate
     double intYearsMonths = dblTrmLoanRate [intYears] [0];                    // Calculates Loan Term in Months
int months = (int)intYearsMonths * 12;                          // Devides by months
double interestRateMonthly = (intRate / 12); // Devides Rate
          double payment = dblLoanAmount * intRate / (1 - (Math.pow(1/(1 + intRate), months))); // Calculates monthly payment
     double dblRmnLoan = dblLoanAmount;                              //Left over balance
     double txtPaymentInterest = 0;                                   // Payment
     double txtPaymentPrincipal = 0;                                   // Payment of principal
NumberFormat currency = NumberFormat.getCurrencyInstance(Locale.US); // Curreny format
     txtPayment.setText(currency.format(payment));
          boxSpace.setText("Month\tPrincipal\tInterest\tBalance Left\n");
          for (;months > 0 ; months -- )
          txtPaymentInterest = (dblRmnLoan * intRate);
                    txtPaymentPrincipal = (payment - txtPaymentInterest);          // Calculates monthly payment
               dblRmnLoan = (dblRmnLoan - txtPaymentPrincipal);
                    boxSpace.setCaret (new DefaultCaret());                    // Scroll position
                    boxSpace.append(String.valueOf(months) + "\t" +               // Table data
                    currency.format(txtPaymentPrincipal) + "\t" +
               currency.format(txtPaymentInterest) + "\t" +
               currency.format(dblRmnLoan) + "\n");
if(command == reset)
                         Clears fields
                    txtYearsInput.setText(null);
                    txtInterestRate.setText(null);
          txtYears.setText(null);
                    txtPayment.setText(null);
     boxSpace.setText(null);
                    public static void main(String[] args)                               //This is the signature of the entry point of all the desktop apps
          new MPC();
}

Answer 1

This portion to be exact. All the buttons work for me except this one. I need to calculate user input and also use the fixed data that can be found in the dblTrmLoanRate array. When I choos to use user input instead, the program either crashes or for some reason uses the year7InterestRateBtn instead.
               if (command == btnCalc)
                    //dblLoanAmount = Double.parseDouble(txtTotalMort.getText() ); // Loan amount
                    //interestRate = Double.parseDouble(txtInterestRate.getText() ); // /100 )/ 12; // Devides rate
                    intRate = (Double.parseDouble(txtInterestRate.getText() )/100 )/ 12;
                    //int intYearsMonths = Integer.parseInt(txtYearsInput.getText() );// * 12; //Multiplies loan length
                    int months = Integer.parseInt(txtYearsInput.getText() )* 12;
I was going to leave out the remed portion but thought it might help you with the navigation. I am sorry I did not use code tags, but I am going to go find out what those are and use them in the future.