// Project 1-1: A Simple stopwatch. 
 
import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import java.util.*; 
  
class StopWatch implements ActionListener { 
 
  JLabel jlab;  
  long start; // holds the start time in milliseconds 
 
  StopWatch() { 
 
    // Create a new JFrame container. 
    JFrame jfrm = new JFrame("A Simple Stopwatch"); 
 
    // Specify FlowLayout for the layout manager. 
    jfrm.getContentPane().setLayout(new FlowLayout()); 
 
    // Give the frame an initial size. 
    jfrm.setSize(230, 90); 
 
    // Terminate the program when the user closes the application. 
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
 
    // Make two buttons. 
    JButton jbtnStart = new JButton("Start"); 
    JButton jbtnStop = new JButton("Stop"); 
 
    // Add action listeners. 
    jbtnStart.addActionListener(this); 
    jbtnStop.addActionListener(this); 
 
    // Add the buttons to the content pane. 
    jfrm.getContentPane().add(jbtnStart);  
    jfrm.getContentPane().add(jbtnStop);  
 
    // Create a text-based label. 
    jlab = new JLabel("Press Start to begin timing."); 
 
    // Add the label to the frame. 
    jfrm.getContentPane().add(jlab); 
 
    // Display the frame. 
    jfrm.setVisible(true); 
  } 
 
  // Handle button events. 
  public void actionPerformed(ActionEvent ae) { 
    Calendar cal = Calendar.getInstance(); // get the current system time 
 
    if(ae.getActionCommand().equals("Start")) { 
      // Store start time. 
      start = cal.getTimeInMillis(); 
      jlab.setText("Stopwatch is Running..."); 
    } 
    else 
      // Compute the elapsed time. 
      jlab.setText("Elapsed time is " 
           + (double) (cal.getTimeInMillis() - start)/1000); 
  } 
 
  public static void main(String args[]) { 
 
    // Create the frame on the event dispatching thread. 
    SwingUtilities.invokeLater(new Runnable() { 
      public void run() { 
        new StopWatch(); 
      } 
    }); 
  } 
 
}