Package org.apache.commons.lang3.time

# Class StopWatch

java.lang.Object
org.apache.commons.lang3.time.StopWatch

public class StopWatch extends Object
`StopWatch` provides a convenient API for timings.

To start the watch, call `start()` or `createStarted()`. At this point you can:

- `split()` the watch to get the time whilst the watch continues in the background. `unsplit()` will remove the effect of the split. At this point, these three options are available again.
- `suspend()` the watch to pause it. `resume()` allows the watch to continue. Any time between the suspend and resume will not be counted in the total. At this point, these three options are available again.
- `stop()` the watch to complete the timing session.

It is intended that the output methods `toString()` and `getTime()` should only be called after stop, split or suspend, however a suitable result will be returned at other points.

NOTE: As from v2.1, the methods protect against inappropriate calls. Thus you cannot now call stop before start, resume before suspend or unsplit before split.

1. `split()`, `suspend()`, or `stop()` cannot be invoked twice
2. `unsplit()` may only be called if the watch has been `split()`
3. `resume()` may only be called if the watch has been `suspend()`
4. `start()` cannot be called twice without calling `reset()`

This class is not thread-safe

Since:
  2.0

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `StopWatch()`
  Constructor.
  `StopWatch(String message)`
  Constructs a new instance.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static StopWatch`
  `create()`
  Creates a StopWatch.
  `static StopWatch`
  `createStarted()`
  Creates and starts a StopWatch.
  `String`
  `formatSplitTime()`
  Formats the split time with `DurationFormatUtils.formatDurationHMS(long)`.
  `String`
  `formatTime()`
  Formats the time formatted with `DurationFormatUtils.formatDurationHMS(long)`.
  `String`
  `getMessage()`
  Gets the message for string presentation.
  `long`
  `getNanoTime()`
  Gets the elapsed time in nanoseconds.
  `long`
  `getSplitNanoTime()`
  Gets the split time in nanoseconds.
  `long`
  `getSplitTime()`
  Gets the split time on the StopWatch.
  `long`
  `getStartTime()`
  Gets the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
  `long`
  `getStopTime()`
  Gets the time this StopWatch was stopped in milliseconds, between the current time and midnight, January 1, 1970 UTC.
  `long`
  `getTime()`
  Gets the time on the StopWatch.
  `long`
  `getTime(TimeUnit timeUnit)`
  Gets the time in the specified TimeUnit.
  `boolean`
  `isStarted()`
  Tests whether the StopWatch is started.
  `boolean`
  `isStopped()`
  Tests whether StopWatch is stopped.
  `boolean`
  `isSuspended()`
  Tests whether the StopWatch is suspended.
  `void`
  `reset()`
  Resets the StopWatch.
  `void`
  `resume()`
  Resumes the StopWatch after a suspend.
  `void`
  `split()`
  Splits the time.
  `void`
  `start()`
  Starts the StopWatch.
  `void`
  `stop()`
  Stops the StopWatch.
  `void`
  `suspend()`
  Suspends the StopWatch for later resumption.
  `String`
  `toSplitString()`
  Gets a summary of the split time that the StopWatch recorded as a string.
  `String`
  `toString()`
  Gets a summary of the time that the StopWatch recorded as a string.
  `void`
  `unsplit()`
  Removes a split.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### StopWatch

    public StopWatch()
    Constructor.

  - ### StopWatch

    public StopWatch(String message)
    Constructs a new instance.
    Parameters:
      `message` - A message for string presentation.
    Since:
      3.10

- ## Method Details

  - ### create

    public static StopWatch create()
    Creates a StopWatch.
    Returns:
      StopWatch a StopWatch.
    Since:
      3.10

  - ### createStarted

    public static StopWatch createStarted()
    Creates and starts a StopWatch.
    Returns:
      StopWatch a started StopWatch.
    Since:
      3.5

  - ### formatSplitTime

    public String formatSplitTime()
    Formats the split time with `DurationFormatUtils.formatDurationHMS(long)`.
    Returns:
      the split time formatted by `DurationFormatUtils.formatDurationHMS(long)`.
    Since:
      3.10

  - ### formatTime

    public String formatTime()
    Formats the time formatted with `DurationFormatUtils.formatDurationHMS(long)`.
    Returns:
      the time formatted by `DurationFormatUtils.formatDurationHMS(long)`.
    Since:
      3.10

  - ### getMessage

    public String getMessage()
    Gets the message for string presentation.
    Returns:
      the message for string presentation.
    Since:
      3.10

  - ### getNanoTime

    public long getNanoTime()
    Gets the elapsed time in nanoseconds.

    This is either the time between the start and the moment this method is called, or the amount of time between start and stop.

    Returns:
      the elapsed time in nanoseconds.
    Since:
      3.0
    See Also:
      - `System.nanoTime()`

  - ### getSplitNanoTime

    public long getSplitNanoTime()
    Gets the split time in nanoseconds.

    This is the time between start and latest split.

    Returns:
      the split time in nanoseconds
    Throws:
      `IllegalStateException` - if the StopWatch has not yet been split.
    Since:
      3.0

  - ### getSplitTime

    public long getSplitTime()
    Gets the split time on the StopWatch.

    This is the time between start and latest split.

    Returns:
      the split time in milliseconds
    Throws:
      `IllegalStateException` - if the StopWatch has not yet been split.
    Since:
      2.1

  - ### getStartTime

    public long getStartTime()
    Gets the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    Returns:
      the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    Throws:
      `IllegalStateException` - if this StopWatch has not been started
    Since:
      2.4

  - ### getStopTime

    public long getStopTime()
    Gets the time this StopWatch was stopped in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    Returns:
      the time this StopWatch was started in milliseconds, between the current time and midnight, January 1, 1970 UTC.
    Throws:
      `IllegalStateException` - if this StopWatch has not been started
    Since:
      3.12.0

  - ### getTime

    public long getTime()
    Gets the time on the StopWatch.

    This is either the time between the start and the moment this method is called, or the amount of time between start and stop.

    Returns:
      the time in milliseconds

  - ### getTime

    public long getTime(TimeUnit timeUnit)
    Gets the time in the specified TimeUnit.

    This is either the time between the start and the moment this method is called, or the amount of time between start and stop. The resulting time will be expressed in the desired TimeUnit with any remainder rounded down. For example, if the specified unit is `TimeUnit.HOURS` and the StopWatch time is 59 minutes, then the result returned will be `0`.

    Parameters:
      `timeUnit` - the unit of time, not null
    Returns:
      the time in the specified TimeUnit, rounded down
    Since:
      3.5

  - ### isStarted

    public boolean isStarted()
    Tests whether the StopWatch is started. A suspended StopWatch is also started watch.
    Returns:
      boolean If the StopWatch is started.
    Since:
      3.2

  - ### isStopped

    public boolean isStopped()
    Tests whether StopWatch is stopped. The StopWatch which's not yet started and explicitly stopped StopWatch is considered as stopped.
    Returns:
      boolean If the StopWatch is stopped.
    Since:
      3.2

  - ### isSuspended

    public boolean isSuspended()
    Tests whether the StopWatch is suspended.
    Returns:
      boolean If the StopWatch is suspended.
    Since:
      3.2

  - ### reset

    public void reset()
    Resets the StopWatch. Stops it if need be.

    This method clears the internal values to allow the object to be reused.

  - ### resume

    public void resume()
    Resumes the StopWatch after a suspend.

    This method resumes the watch after it was suspended. The watch will not include time between the suspend and resume calls in the total time.

    Throws:
      `IllegalStateException` - if the StopWatch has not been suspended.

  - ### split

    public void split()
    Splits the time.

    This method sets the stop time of the watch to allow a time to be extracted. The start time is unaffected, enabling `unsplit()` to continue the timing from the original start point.

    Throws:
      `IllegalStateException` - if the StopWatch is not running.

  - ### start

    public void start()
    Starts the StopWatch.

    This method starts a new timing session, clearing any previous values.

    Throws:
      `IllegalStateException` - if the StopWatch is already running.

  - ### stop

    public void stop()
    Stops the StopWatch.

    This method ends a new timing session, allowing the time to be retrieved.

    Throws:
      `IllegalStateException` - if the StopWatch is not running.

  - ### suspend

    public void suspend()
    Suspends the StopWatch for later resumption.

    This method suspends the watch until it is resumed. The watch will not include time between the suspend and resume calls in the total time.

    Throws:
      `IllegalStateException` - if the StopWatch is not currently running.

  - ### toSplitString

    public String toSplitString()
    Gets a summary of the split time that the StopWatch recorded as a string.

    The format used is ISO 8601-like, [message ]hours:minutes:seconds.milliseconds.

    Returns:
      the split time as a String
    Since:
      2.1, 3.10 Returns the prefix `"message "` if the message is set.

  - ### toString

    public String toString()
    Gets a summary of the time that the StopWatch recorded as a string.

    The format used is ISO 8601-like, [message ]hours:minutes:seconds.milliseconds.

    Overrides:
      `toString` in class `Object`
    Returns:
      the time as a String
    Since:
      3.10 Returns the prefix `"message "` if the message is set.

  - ### unsplit

    public void unsplit()
    Removes a split.

    This method clears the stop time. The start time is unaffected, enabling timing from the original start point to continue.

    Throws:
      `IllegalStateException` - if the StopWatch has not been split.