Creating a Stopwatch in Java

In this tutorial, we will create a simple stopwatch using Java. The stopwatch will have the functionality to start, stop, and reset. Let's dive into the Java code:

import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class StopwatchSwing implements ActionListener { private JFrame frame; private JButton startButton; private JButton stopButton; private JButton resetButton; private JLabel elapsedTimeLabel; private long startTime; private long elapsedTime; private boolean running; private Timer timer; public StopwatchSwing() { // Initialize the stopwatch components startButton = new JButton("Start"); stopButton = new JButton("Stop"); resetButton = new JButton("Reset"); elapsedTimeLabel = new JLabel("0.000 seconds", SwingConstants.CENTER); elapsedTimeLabel.setFont(new Font("SansSerif", Font.BOLD, 32)); // Set the layout and size of the stopwatch window frame = new JFrame("Stopwatch"); frame.setLayout(new BorderLayout()); frame.setPreferredSize(new Dimension(400, 200)); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Create a panel to hold the buttons JPanel buttonPanel = new JPanel(); buttonPanel.add(startButton); buttonPanel.add(stopButton); buttonPanel.add(resetButton); // Add the buttons and elapsed time label to the stopwatch window frame.add(buttonPanel, BorderLayout.NORTH); frame.add(elapsedTimeLabel, BorderLayout.CENTER); // Add action listeners to the buttons startButton.addActionListener(this); stopButton.addActionListener(this); resetButton.addActionListener(this); // Initialize the stopwatch variables startTime = 0; elapsedTime = 0; running = false; // Initialize the timer timer = new Timer(100, this); timer.setInitialDelay(0); // Pack and display the stopwatch window frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } @Override public void actionPerformed(ActionEvent e) { if (e.getSource() == startButton) { startTime = System.currentTimeMillis(); running = true; timer.start(); } else if (e.getSource() == stopButton) { elapsedTime += System.currentTimeMillis() - startTime; running = false; timer.stop(); } else if (e.getSource() == resetButton) { elapsedTime = 0; elapsedTimeLabel.setText("0.000 seconds"); timer.stop(); } else if (running) { long currentTime = System.currentTimeMillis(); long elapsed = currentTime - startTime; elapsedTime += elapsed; startTime = currentTime; String elapsedTimeString = String.format("%.3f seconds", elapsedTime / 1000.0); elapsedTimeLabel.setText(elapsedTimeString); } } public static void main(String[] args) { SwingUtilities.invokeLater(StopwatchSwing::new); } }