Go4Expert - Could someone please tell me why my assignment didn't work.

Hi all. I'm taking my first course in Java and am terrible at it. I failed the last assignment we did and I was wondering if someone could tell me how to fix it so I don't run into the same problems on the next lab. We were instructed to create a working tip calculator. Thank you so much for your help in advance!
Code:
import java.awt.*;



import javax.swing.*;





public class Lab5 extends JApplet implements ActionListener

{    

    

    

public void actionPerformed(ActionEvent e);

{    

    //determines what will occur when the buttons are pressed

    if(e.getSource()==submit)

        performCalculations();

    else

        ClearGUI();

}    



public void performCalculations()

{

    double billAmountEntered = Double.parseDouble(totalBill.getText().trim());

    int numCustomers = Integer.parseInt(people.getText().trim());

    string country = (string)countries.getSelectedItem();

    string typeOfTip = (string)tip.getSelectedIndex();

    pic = getImage(getCodeBase(),"Images/"+country+".png");

    double percentOfTip;

    double taxPercentUsed;

    double totalCalculation;

    double amountPerPersonCalculation;

    double tipAmount;

    double taxAmount;

    



    

    //calculates the tip according to the user input

    if(country==0)

        ;

        else if(country==1)

            typeOfTip = tip.getSelectedIndex();

            taxPercentUsed = .08;

            billAmount.setText(billAmountEntered);

            taxAmountDisplay.setText(taxAmount);

            totalBill.setText(totalCalculation);

            personAmount.setText(amountPerPersonCalculation);

            if(typeOfTip==0)

                tip=0.0;

                else if(typeOfTip==1)

                    tip=.13;

                    else if(typeOfTip==2)

                        tip=.15;

                        else

                            tip=.20;

            percentOfTip = tip;

            tipAmount = billAmountEntered * percentOfTip;

            taxAmount = billAmountEntered * taxPercentUsed;

            totalCalculation = billAmountEntered + tipAmount + taxAmount;

        else if(country==2)

            typeOfTip = tip.getSelectedIndex();

            taxPercentUsed = .05;

            billAmount.setText(billAmountEntered);

            taxAmountDisplay.setText(taxAmount);

            totalBill.setText(totalCalculation);

            personAmount.setText(amountPerPersonCalculation);

            if(typeOfTip==0)

                tip=0.0;

                else if(typeOfTip==1)

                    tip=.13;

                    else if(typeOfTip==2)

                        tip=.15;

                        else if(typeOfTip==3)

                            tip=.20;

            percentOfTip = tip;

            tipAmount = billAmountEntered * percentOfTip;

            taxAmount = billAmountEntered * taxPercentUsed;

            totalCalculation = billAmountEntered + tipAmount + taxAmount;

        else if(country==3)

            typeOfTip = tip.getSelectedIndex();

            taxPercentUsed = .08;

            billAmount.setText(billAmountEntered);

            taxAmountDisplay.setText(taxAmount);

            totalBill.setText(totalCalculation);

            personAmount.setText(amountPerPersonCalculation);

            if(typeOfTip==0)

                tip=0.0;

                else if(typeOfTip==1)

                    tip=.10;

                    else if(typeOfTip==2)

                        tip=.12;

                        else if(typeOfTip==3)

                            tip=.15;

            percentOfTip = tip;

            tipAmount = billAmountEntered * percentOfTip;

            taxAmount = billAmountEntered * taxPercentUsed;

            totalCalculation = billAmountEntered + tipAmount + taxAmount;



}



public void ClearGui()

{   

    //sets the applet to its original state

    tip.setSelectedIndex(0);

    countries.setSelectedIndex(0);

    includeTax.setSelected(true);

    

    validate();

}



//the layout code

public void init()

{

    setLayout(new BorderLayout());

    

    JLabel title = new JLabel("Multi Country Tip Calculator");

    JComboBox countries = new JComboBox();

    JLabel checkAmount = new JLabel("Check Amount:");

    JTextField billAmount = new JTextField(8);

    JLabel tax = new JLabel("Tax:");

    JTextField taxAmountDisplay = new JTextField(8);

    JCheckBox includeTax = new JCheckBox("Include Tax");

    DefaultListModel myModel = new DefaultListModel();

    JList tip = new JList(myModel);

    JLabel tipPercentUsed = new JLabel("Tip % Used:");

    JTextField tipPercentSelection = new JTextField(8);

    JLabel total = new JLabel("Total:");

    JTextField totalBill = new JTextField(8);

    JLabel numberOfPeople = new JLabel("Number of People:");

    JTextField people = new JTextField(3);

    JLabel amountPerPerson = new JLabel("Amount Per Person:");

    JTextField personAmount = new JTextField(8);

    JButton submit = new JButton("Submit");

    JButton clear = new JButton("Clear");

    

    //adds a JPanel and its components to the north portion of the border layout

    JPanel north = new JPanel(new FlowLayout());

    add(north, BorderLayout.NORTH);

    north.add(title);

    

    //adds a JPanel and its components to the west portion of the border layout

    JPanel west = new JPanel(new FlowLayout());

    add(west, BorderLayout.WEST);

    west.add(countries);

    

    //adds a JPanel and its components to the east portion of the border layout

    JPanel east = new JPanel(new GridLayout(2,1));

    add(east, BorderLayout.EAST);

    east.add(tip);

    east.add(includeTax);

    

    //adds a JPanel and its components to the center portion of the border layout

    JPanel center = new JPanel(new GridLayout(5,2));

    add(center, BorderLayout.CENTER);

    center.add(tipPercentUsed);

    center.add(tipPercentSelection);

    center.add(checkAmount);

    center.add(billAmount);

    center.add(tax);

    center.add(taxAmountDisplay);

    center.add(numberOfPeople);

    center.add(people);

    

    //adds a JPanel and its components to the south portion of the border layout

    JPanel south = new JPanel(new GridLayout(4,4));

    add(south, BorderLayout.SOUTH);

    south.add(total);

    south.add(totalBill);

    south.add(amountPerPerson);

    south.add(personAmount);

    south.add(submit);

    south.add(clear);

    

    

    //sets the title's font, color, size, and location

    title.setForeground(Color.blue);

    title.setFont(new Font("Serif",Font.BOLD,40));

    title.setLocation(200,200);

            

    //adds items to the combo box

    countries.addItem("Please Select A Country");

    countries.addItem("United States");

    countries.addItem("Italy");

    countries.addItem("France");

            

    //adds items to the list

    myModel.addElement("No tip");

    myModel.addElement("Minimum tip");

    myModel.addElement("Normal tip");

    myModel.addElement("High tip");

    

    //changes the background color

    north.setBackground(Color.ORANGE);

    south.setBackground(Color.ORANGE);

    west.setBackground(Color.ORANGE);

    center.setBackground(Color.ORANGE);

    east.setBackground(Color.ORANGE);

    

    //sets all the JLabels' colors 

    total.setForeground(Color.blue);

    amountPerPerson.setForeground(Color.blue);

    checkAmount.setForeground(Color.blue);

    tax.setForeground(Color.blue);

    tipPercentUsed.setForeground(Color.blue);

    numberOfPeople.setForeground(Color.blue);

    

    //sets the size of "Total" and "Amount Per Person"

    total.setFont(new Font("Serif",Font.BOLD,20));

    amountPerPerson.setFont(new Font("Serif",Font.BOLD,20));

    

    //sets the color of the JButtons

    submit.setBackground(Color.red);

    submit.setForeground(Color.blue);

    clear.setBackground(Color.red);

    clear.setForeground(Color.blue);

    

    //sets the colors in the JList

    tip.setBackground(Color.white);

    tip.setForeground(Color.blue);

    

    //sets the colors of the JCheckBox

    includeTax.setForeground(Color.blue);

    includeTax.setBackground(Color.white);

    

    //sets the colors of the JComboBox

    countries.setForeground(Color.blue);

    countries.setBackground(Color.white);

    

}