CS1103 Programming Assignment Unit 7 - A stopwatch

Questions

Please write a custom component that acts as a simple stop-watch. Specifically, when the user clicks on it, this component starts timing; when the user clicks again, it displays the time between the two clicks; clicking a third time starts another timer, etc; while it is timing, the label displays the elapsed time since the timer was started.

1. Programs

StopWatchLabel.java

import java.awt.event.*;
import javax.swing.*;
/**
 * A custom component that acts as a simple stop-watch.
 * When the user clicks on it, this component starts timing.
 * When the user clicks again, it displays the time between the two clicks.
 * Clicking a third time starts another timer, etc.
 * While it is timing, the label displays the elapsed time since the timer was started.
 */
public class StopWatchLabel extends JLabel implements MouseListener, ActionListener {
    private long startTime; // Start time of timer. Time is measured in milliseconds.
    private boolean running; // True when the timer is running.
    private Timer timer; // Create a timer

    /**
     * Constructor sets initial text on the label to "Click to start timer."
     * And sets up a mouse listener, so the label can respond to clicks.
     */
    public StopWatchLabel() {
        super(" Click to start timer. ", JLabel.CENTER);
        addMouseListener(this);
    }
    /**
     * Tells whether the timer is currently running.
     */
    public boolean isRunning() {
        return running;
    }

    /**
     * Compute the elapsed time since the timer was started.
     */
    public void actionPerformed(ActionEvent evt) {
        long time = (System.currentTimeMillis() - startTime) / 1000;
        setText("Timing: " + time + " seconds");
    }

    /**
     * React when the user presses the mouse by starting or stopping the timer,
     * and displaying the elapsed time that is shown on the label.
     */
    public void mousePressed(MouseEvent evt) {
        if (running == false) {
            // Record the time and create the timer when the stopwatch is started
            running = true;
            startTime = evt.getWhen(); // Time when mouse was clicked.
            if (timer == null) {
                // Use a delay of 200 milliseconds for the timer
                timer = new Timer(200,this);
                // Call the start() to run the timer
                timer.start();
            }
            else
                timer.restart();
        }
        else {
            // Stop the timer, and compute the elapsed time since the timer was started and display it.
            timer.stop();
            running = false;
            long endTime = evt.getWhen();
            double seconds = (endTime - startTime) / 1000.0;
            setText("Time: " + seconds + " seconds");
        }
    }
    public void mouseReleased(MouseEvent evt) { }
    public void mouseClicked(MouseEvent evt) { }
    public void mouseEntered(MouseEvent evt) { }
    public void mouseExited(MouseEvent evt) { }
}

StopWatchLabelTest.java

import javax.swing.*;
import java.awt.*;

/**
 * Tests the custom component classes StopWatchLabel by adding them both to a panel.
 */
public class StopWatchLabelTest extends JPanel {

    private StopWatchLabel timer;

    /**
     * The StopWatchLabel define components.
     * But components don’t stand on their own. We have to add them to a panel.
     */
    public StopWatchLabelTest() {
        // Uses a FlowLayout as its layout manager
        setLayout(new FlowLayout());

        timer = new StopWatchLabel();
        timer.setBackground(Color.white);
        timer.setForeground(Color.blue);
        timer.setOpaque(true);
        timer.setFont(new Font("Serif", Font.PLAIN, 20));
        add(timer);
    }

    /**
     * The main routine simply opens a window that shows a StopWatchLabelTest panel.
     */
    public static void main(String[] args) {
        JFrame window = new JFrame("StopWatchLabelTest");
        StopWatchLabelTest content = new StopWatchLabelTest();
        window.setContentPane(content);
        window.setSize(350, 90);
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        window.setLocation((screenSize.width - window.getWidth()) / 2, (screenSize.height - window.getHeight()) / 2);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
    }
}

2. Outputs

Before timing：

During timing：

After timing:

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This is the ending, thanks for reading.

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