Java Simple Stopwatch Project

Last update on October 05 2024 13:10:15 (UTC/GMT +8 hours)

Java Project - Measure Time Using Millis or Nano:

Simple Stopwatch:

Input: Start and stop commands.
Output: Elapsed time when the stopwatch is stopped.

Example:

Input: "Start stopwatch"
Output: "Stopwatch started."
After some time: "Stop stopwatch"
Output: "Elapsed time: 12.34 seconds."

Solution 1: Simple Stopwatch using System.currentTimeMillis()

Code:

import java.util.Scanner;

public class Stopwatch {
    // Variables to store start and stop times
    private long startTime;
    private long stopTime;

    // Method to start the stopwatch
    public void start() {
        startTime = System.currentTimeMillis();  // Capture the start time
        System.out.println("Stopwatch started.");
    }

    // Method to stop the stopwatch and calculate elapsed time
    public void stop() {
        stopTime = System.currentTimeMillis();  // Capture the stop time
        long elapsedTime = stopTime - startTime;  // Calculate the elapsed time
        System.out.println("Elapsed time: " + (elapsedTime / 1000.0) + " seconds.");
    }

    // Main method to run the stopwatch
    public static void main(String[] args) {
        Stopwatch stopwatch = new Stopwatch();
        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter 'start' to begin the stopwatch:");
        String input = scanner.nextLine();

        if (input.equalsIgnoreCase("start")) {
            stopwatch.start();  // Start the stopwatch
        }

        System.out.println("Enter 'stop' to stop the stopwatch:");
        input = scanner.nextLine();

        if (input.equalsIgnoreCase("stop")) {
            stopwatch.stop();  // Stop the stopwatch
        }

        scanner.close();
    }
}

Output:

Enter 'start' to begin the stopwatch:
 start
Stopwatch started.

Enter 'stop' to stop the stopwatch:
 stop
Elapsed time: 8.425 seconds.

Explanation :

Uses System.currentTimeMillis() to record time in milliseconds.
Starts and stops the stopwatch using user input.
Calculates and prints the elapsed time in seconds.

Solution 2: Simple Stopwatch using nanoTime()

Code:

import java.util.Scanner;

public class NanoStopwatch {
    // Variables to store start and stop times
    private long startTime;
    private long stopTime;

    // Method to start the stopwatch
    public void start() {
        startTime = System.nanoTime();  // Capture the start time in nanoseconds
        System.out.println("Stopwatch started.");
    }

    // Method to stop the stopwatch and calculate elapsed time
    public void stop() {
        stopTime = System.nanoTime();  // Capture the stop time in nanoseconds
        long elapsedTime = stopTime - startTime;  // Calculate the elapsed time
        System.out.println("Elapsed time: " + (elapsedTime / 1_000_000_000.0) + " seconds.");
    }

    // Main method to run the stopwatch
    public static void main(String[] args) {
        NanoStopwatch stopwatch = new NanoStopwatch();
        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter 'start' to begin the stopwatch:");
        String input = scanner.nextLine();

        if (input.equalsIgnoreCase("start")) {
            stopwatch.start();  // Start the stopwatch
        }

        System.out.println("Enter 'stop' to stop the stopwatch:");
        input = scanner.nextLine();

        if (input.equalsIgnoreCase("stop")) {
            stopwatch.stop();  // Stop the stopwatch
        }

        scanner.close();
    }
}

Output:

Enter 'start' to begin the stopwatch:
 start
Stopwatch started.

Enter 'stop' to stop the stopwatch:
 stop
Elapsed time: 16.259088781 seconds.

Explanation:

Uses System.nanoTime() for higher precision timing in nanoseconds.
Same user input logic as the first solution, but with greater accuracy.
Outputs the time in seconds after converting nanoseconds.

Java Code Editor: