New to Java

I am new to Java so be nice.

I am having a problem compiling my program. To make a quick summary of what it is, I am creating a mortgage calculator (applet) that will calculate a monthly payment based on the user's input of the Principal, Loan Term, and Interest Rate.

I keep getting the error: "Missing Return Statement }" And it states that the line is located at the second to the last closing brackets. I don't understand what I am doing wrong. I have already double checked my closing brackets and that didn't seem to be the problem. But is there a line of code that I am missing?

Would anyone mind giving me some guidance so that I may be able to correct my mistake please? Any help is greatly appreciated. Thanks

import java.text.*;
import java.awt.*;
import java.applet.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.math.*;
import java.util.*;
import javax.swing.text.JTextComponent.*;
import javax.swing.JTextField.*;
import javax.swing.event.ChangeListener.*;
import java.awt.event.ActionListener.*;
import java.lang.Integer.*;
import java.lang.*;
import javax.swing.event.*;
import javax.swing.text.*;


public class test4 extends JApplet implements ActionListener
{
	JLabel heading = new JLabel("McBride Financial Services \n" + "Mortgage Calculator \n");
	Font newFontOne = new Font("TimesRoman", Font.BOLD, 20);
	Font newFontTwo = new Font("TimesRoman", Font.ITALIC, 16);
	JButton calculate = new JButton("Calculate");
	JLabel instructions = new JLabel("Please fill in all areas below");

	private double principalAmount;
	private JLabel principalLabel = new JLabel("Principal Amount");
	private NumberFormat principalFormat;
	private JFormattedTextField enterPrincipal = new JFormattedTextField(principalFormat);

	private int loanTermLength;
	private JLabel loanTermLabel = new JLabel("Loan Term");
	private NumberFormat loanTermFormat;
	private JFormattedTextField enterLoanTerm = new JFormattedTextField(loanTermFormat);

	private double loanInterestRate;
	private JLabel interestRateLabel = new JLabel("Interest Rate");
	private NumberFormat interestRateFormat;
	private JFormattedTextField enterInterestRate = new JFormattedTextField(interestRateFormat);

	private double finalPayment;
	private JLabel finalPaymentLabel = new JLabel("Monthly Payment is: $ ");
	private NumberFormat finalPaymentFormat;
	private JFormattedTextField displayFinalPayment = new JFormattedTextField(finalPaymentFormat);


	public void init()
	{

		Container con = getContentPane();
		heading.setFont(newFontOne);
		instructions.setFont(newFontTwo);
		con.add(heading);
		con.add(instructions);
		con.add(enterPrincipal);
		con.add(enterLoanTerm);
		con.add(enterInterestRate);
		con.add(calculate);
		calculate.addActionListener(this);
		enterPrincipal.requestFocus();
	}

	public void repaint()
	{
		repaint();
	}

	public void actionPerformed(ActionEvent e)
	{

		Object source = e.getSource();

		if (source == enterPrincipal)
		{
			principalAmount = ((Number)enterPrincipal.getValue()).doubleValue();
		}

		else if (source == enterLoanTerm)
		{
			loanTermLength = ((Number)enterLoanTerm.getValue()).intValue();
		}

		else if (source == enterInterestRate)
		{
			loanInterestRate = ((Number)enterInterestRate.getValue()).doubleValue();
		}

	}

	private void formatting()
	{
		principalFormat = NumberFormat.getNumberInstance();
		loanTermFormat = NumberFormat.getInstance();
		interestRateFormat = NumberFormat.getPercentInstance();
		finalPaymentFormat = NumberFormat.getCurrencyInstance();

	}


	public double calculatePayment(double payment, double totalPrincipal, double intRate, double term, int totalPayments, double periodInterest)
	{
			periodInterest = intRate / 12;
			totalPayments = loanTermLength * 12;
			totalPrincipal = ((Number)enterPrincipal.getValue()).doubleValue();
			intRate = ((Number)enterInterestRate.getValue()).doubleValue();
			term = ((Number)enterLoanTerm.getValue()).intValue();
			loanInterestRate = intRate / 100;


		if(totalPrincipal >= 0.01)
		{
			return payment = totalPrincipal * (periodInterest * Math.pow((1 + periodInterest), totalPayments)) / ((Math.pow((1 + periodInterest), totalPayments) - 1));

		}
	}
}