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Add split-second-stopwatch exercise #2968 (#2977)
* Add split-second-stopwatch exercise #2968 Add split-second-stopwatch exercise Implement the split-second-stopwatch practice exercise with: - State management (ready/running/stopped) - Time tracking for current lap and total elapsed time - Lap functionality with previous laps history - Start, stop, reset operations with proper state validation - Error handling for invalid state transitions - Time formatting in HH:MM:SS format - Mock time advancement for testing Includes reference solution, starter implementation, and comprehensive test suite covering all canonical data test cases. * Add split-second-stopwatch exercise #2968 git add . git commit -m "Add split-second-stopwatch exercise Implement the split-second-stopwatch practice exercise with: - State management (ready/running/stopped) - Time tracking for current lap and total elapsed time - Lap functionality with previous laps history - Start, stop, reset operations with proper state validation - Error handling for invalid state transitions - Time formatting in HH:MM:SS format - Mock time advancement for testing Includes reference solution, starter implementation, and comprehensive test suite covering all canonical data test cases." * Add split-second-stopwatch exercise #2968 #2977 Gradle files added to new practice exercise. Gradle/wrapper directories and files copied into split-second-stopwatch exercise as requested. * Add split-second-stopwatch exercise #2968 #2977 Prerequisites and difficulty updated in main config.json file. * Add split-second-stopwatch exercise #2968 #2977 config.json format updated. * Add split-second-stopwatch exercise #2968 #2977 Add remaining gradle files to split-second-stopwatch exercise. * Update exercises/practice/split-second-stopwatch/src/test/java/SplitSecondStopwatchTest.java Co-authored-by: Kah Goh <[email protected]> * Update exercises/practice/split-second-stopwatch/.meta/src/reference/java/SplitSecondStopwatch.java Co-authored-by: Kah Goh <[email protected]> * Add split-second-stopwatch exercise #2968 #2977 main config.json updated to reorder new practice exercise. --------- Co-authored-by: Kah Goh <[email protected]> Co-authored-by: Jagdish Prajapati <[email protected]>
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‎config.json‎

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],
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"difficulty": 4
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},
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{
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"slug": "split-second-stopwatch",
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"name": "Split-Second Stopwatch",
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"uuid": "9510c0ae-9977-4260-8991-0e8e849094b0",
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"practices": [],
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"prerequisites": [
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"exceptions",
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"if-else-statements"
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],
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"difficulty": 4
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},
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{
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"slug": "sum-of-multiples",
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"name": "Sum of Multiples",

‎exercises/practice/split-second-stopwatch/.docs/instructions.md‎

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# Instructions
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Your task is to build a stopwatch to keep precise track of lap times.
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The stopwatch uses four commands (start, stop, lap, and reset) to keep track of:
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1. The current lap's tracked time
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2. Previously recorded lap times
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What commands can be used depends on which state the stopwatch is in:
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1. Ready: initial state
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2. Running: tracking time
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3. Stopped: not tracking time
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| Command | Begin state | End state | Effect |
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| ------- | ----------- | --------- | -------------------------------------------------------- |
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| Start | Ready | Running | Start tracking time |
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| Start | Stopped | Running | Resume tracking time |
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| Stop | Running | Stopped | Stop tracking time |
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| Lap | Running | Running | Add current lap to previous laps, then reset current lap |
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| Reset | Stopped | Ready | Reset current lap and clear previous laps |

‎exercises/practice/split-second-stopwatch/.docs/introduction.md‎

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# Introduction
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You've always run for the thrill of it — no schedules, no timers, just the sound of your feet on the pavement.
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But now that you've joined a competitive running crew, things are getting serious.
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Training sessions are timed to the second, and every split second counts.
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To keep pace, you've picked up the _Split-Second Stopwatch_ — a sleek, high-tech gadget that's about to become your new best friend.

‎exercises/practice/split-second-stopwatch/.meta/config.json‎

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{
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"authors": [
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"EmmanuelBerkowicz"
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],
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"files": {
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"solution": [
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"src/main/java/SplitSecondStopwatch.java"
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],
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"test": [
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"src/test/java/SplitSecondStopwatchTest.java"
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],
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"example": [
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".meta/src/reference/java/SplitSecondStopwatch.java"
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]
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},
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"blurb": "Keep track of time through a digital stopwatch.",
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"source": "Erik Schierboom",
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"source_url": "https://github.com/exercism/problem-specifications/pull/2547"
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}

‎exercises/practice/split-second-stopwatch/.meta/src/reference/java/SplitSecondStopwatch.java‎

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import java.util.ArrayList;
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import java.util.List;
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public class SplitSecondStopwatch {
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/**
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* A split-second stopwatch that tracks elapsed time with lap functionality.
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* Supports start, stop, reset, and lap operations with precise time tracking.
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* Times are formatted in HH:MM:SS format with two-digit precision.
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*
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* @see <a href="https://github.com/exercism/problem-specifications/tree/main/exercises/split-second-stopwatch">
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* Problem Specifications
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* </a>
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*/
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private enum State { READY, RUNNING, STOPPED }
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private State state;
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private long totalCompletedLaps; // Total time from completed laps
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private long currentLapStart; // When current lap started
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private long accumulated; // Accumulated time for current lap when stopped
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private List<String> previousLaps;
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private long mockTime;
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public SplitSecondStopwatch() {
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this.state = State.READY;
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this.totalCompletedLaps = 0;
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this.currentLapStart = 0;
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this.accumulated = 0;
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this.previousLaps = new ArrayList<>();
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this.mockTime = 0;
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}
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public void start() {
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if (state == State.RUNNING) {
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throw new IllegalStateException("cannot start an already running stopwatch");
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}
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currentLapStart = mockTime;
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state = State.RUNNING;
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}
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public void stop() {
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if (state != State.RUNNING) {
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throw new IllegalStateException("cannot stop a stopwatch that is not running");
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}
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accumulated += mockTime - currentLapStart;
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state = State.STOPPED;
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}
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public void reset() {
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if (state != State.STOPPED) {
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throw new IllegalStateException("cannot reset a stopwatch that is not stopped");
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}
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state = State.READY;
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totalCompletedLaps = 0;
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currentLapStart = 0;
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accumulated = 0;
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previousLaps.clear();
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}
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public void lap() {
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if (state != State.RUNNING) {
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throw new IllegalStateException("cannot lap a stopwatch that is not running");
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}
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long currentLapTime = getCurrentLapTime();
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totalCompletedLaps += currentLapTime;
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previousLaps.add(formatTime(currentLapTime));
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// Reset current lap and restart
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accumulated = 0;
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currentLapStart = mockTime;
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}
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public String state() {
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return state.name().toLowerCase();
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}
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public String currentLap() {
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return formatTime(getCurrentLapTime());
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}
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public String total() {
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return formatTime(totalCompletedLaps + getCurrentLapTime());
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}
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public List<String> previousLaps() {
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return new ArrayList<>(previousLaps);
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}
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public void advanceTime(String timeString) {
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String[] parts = timeString.split(":");
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long hours = Long.parseLong(parts[0]);
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long minutes = Long.parseLong(parts[1]);
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long seconds = Long.parseLong(parts[2]);
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long milliseconds = (hours * 3600 + minutes * 60 + seconds) * 1000;
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mockTime += milliseconds;
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}
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private long getCurrentLapTime() {
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switch (state) {
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case READY:
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return 0;
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case RUNNING:
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return accumulated + (mockTime - currentLapStart);
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case STOPPED:
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return accumulated;
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default:
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throw new IllegalStateException("Invalid state");
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}
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}
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private String formatTime(long milliseconds) {
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long totalSeconds = milliseconds / 1000;
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long hours = totalSeconds / 3600;
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long minutes = (totalSeconds % 3600) / 60;
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long seconds = totalSeconds % 60;
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return String.format("%02d:%02d:%02d", hours, minutes, seconds);
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}
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}

‎exercises/practice/split-second-stopwatch/.meta/tests.toml‎

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# This is an auto-generated file.
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#
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# Regenerating this file via `configlet sync` will:
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# - Recreate every `description` key/value pair
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# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
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# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
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# - Preserve any other key/value pair
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#
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# As user-added comments (using the # character) will be removed when this file
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# is regenerated, comments can be added via a `comment` key.
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[ddb238ea-99d4-4eaa-a81d-3c917a525a23]
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description = "new stopwatch starts in ready state"
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[b19635d4-08ad-4ac3-b87f-aca10e844071]
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description = "new stopwatch's current lap has no elapsed time"
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[492eb532-268d-43ea-8a19-2a032067d335]
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description = "new stopwatch's total has no elapsed time"
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[8a892c1e-9ef7-4690-894e-e155a1fe4484]
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description = "new stopwatch does not have previous laps"
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[5b2705b6-a584-4042-ba3a-4ab8d0ab0281]
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description = "start from ready state changes state to running"
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[748235ce-1109-440b-9898-0a431ea179b6]
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description = "start does not change previous laps"
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[491487b1-593d-423e-a075-aa78d449ff1f]
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description = "start initiates time tracking for current lap"
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[a0a7ba2c-8db6-412c-b1b6-cb890e9b72ed]
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description = "start initiates time tracking for total"
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[7f558a17-ef6d-4a5b-803a-f313af7c41d3]
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description = "start cannot be called from running state"
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[32466eef-b2be-4d60-a927-e24fce52dab9]
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description = "stop from running state changes state to stopped"
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[621eac4c-8f43-4d99-919c-4cad776d93df]
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description = "stop pauses time tracking for current lap"
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[465bcc82-7643-41f2-97ff-5e817cef8db4]
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description = "stop pauses time tracking for total"
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[b1ba7454-d627-41ee-a078-891b2ed266fc]
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description = "stop cannot be called from ready state"
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[5c041078-0898-44dc-9d5b-8ebb5352626c]
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description = "stop cannot be called from stopped state"
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[3f32171d-8fbf-46b6-bc2b-0810e1ec53b7]
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description = "start from stopped state changes state to running"
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[626997cb-78d5-4fe8-b501-29fdef804799]
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description = "start from stopped state resumes time tracking for current lap"
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[58487c53-ab26-471c-a171-807ef6363319]
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description = "start from stopped state resumes time tracking for total"
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[091966e3-ed25-4397-908b-8bb0330118f8]
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description = "lap adds current lap to previous laps"
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[1aa4c5ee-a7d5-4d59-9679-419deef3c88f]
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description = "lap resets current lap and resumes time tracking"
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[4b46b92e-1b3f-46f6-97d2-0082caf56e80]
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description = "lap continues time tracking for total"
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[ea75d36e-63eb-4f34-97ce-8c70e620bdba]
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description = "lap cannot be called from ready state"
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[63731154-a23a-412d-a13f-c562f208eb1e]
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description = "lap cannot be called from stopped state"
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[e585ee15-3b3f-4785-976b-dd96e7cc978b]
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description = "stop does not change previous laps"
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[fc3645e2-86cf-4d11-97c6-489f031103f6]
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description = "reset from stopped state changes state to ready"
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[20fbfbf7-68ad-4310-975a-f5f132886c4e]
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description = "reset resets current lap"
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[00a8f7bb-dd5c-43e5-8705-3ef124007662]
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description = "reset clears previous laps"
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[76cea936-6214-4e95-b6d1-4d4edcf90499]
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description = "reset cannot be called from ready state"
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[ba4d8e69-f200-4721-b59e-90d8cf615153]
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description = "reset cannot be called from running state"
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[0b01751a-cb57-493f-bb86-409de6e84306]
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description = "supports very long laps"

‎exercises/practice/split-second-stopwatch/build.gradle‎

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plugins {
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id "java"
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}
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repositories {
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mavenCentral()
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}
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dependencies {
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testImplementation platform("org.junit:junit-bom:5.10.0")
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testImplementation "org.junit.jupiter:junit-jupiter"
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testImplementation "org.assertj:assertj-core:3.25.1"
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testRuntimeOnly "org.junit.platform:junit-platform-launcher"
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}
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test {
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useJUnitPlatform()
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testLogging {
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exceptionFormat = "full"
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showStandardStreams = true
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events = ["passed", "failed", "skipped"]
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}
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}

‎exercises/practice/split-second-stopwatch/gradle/wrapper/gradle-wrapper.jar‎

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‎exercises/practice/split-second-stopwatch/gradle/wrapper/gradle-wrapper.properties‎

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distributionBase=GRADLE_USER_HOME
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distributionPath=wrapper/dists
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distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
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validateDistributionUrl=true
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zipStoreBase=GRADLE_USER_HOME
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zipStorePath=wrapper/dists

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