Java Simple Stopwatch Project

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: