why doesn't this work?

/* Java Program that simulates Stop watch */ import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.text.DecimalFormat; import java.util.Date;

//Class definition public class StopWatch { private JFrame frame; private JPanel panel; private long startTime; //Constructor public Stopwatch() { //Preparing window setGUI(); startTime = 0; } //Main method public static void main(String[] args) { Stopwatch watch = new Stopwatch(); watch.addElements(); } //Creating a window private void setGUI() { //Adding label to frame frame = new JFrame(" "); frame.setSize(280, 130); //Adding window listener frame.addWindowListener(new WindowAdapter() { //Window close event public void windowClosing(WindowEvent windowEvent) { System.exit(0); } }); panel = new JPanel(); panel.setLayout(new FlowLayout()); //Adding frame to Panel frame.add(panel); frame.setVisible(true); } //Adding controls to frame private void addElements() { //Adding label's final JLabel time = new JLabel(" ", JLabel.CENTER); //button final JButton startStopButton = new JButton("Start"); //Button event action listener startStopButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { //If it is initial time if(startTime == 0) { //Creating a Date class object Date dateObj = new Date(); //Getting time startTime = dateObj.getTime(); //Changing text of button startStopButton.setText("Stop"); //Changing text of time time.setText("Running"); } else { //Creating a Date class object Date dateObj = new Date(); //Changing text of button startStopButton.setText("Start"); //Calculating elapsed time double elapsedTime = Double.parseDouble( (dateObj.getTime() - startTime) + ""); //Getting in seconds double timediff = elapsedTime / 1000.0; //Changing text of time time.setText(" " + timediff + " seconds"); } } }); //Adding button panel.add(startStopButton);

//Adding controls to frame panel.add(time); frame.setVisible(true); } }

Why doesn't this work?