Class StopWatch

java.lang.Object

org.springframework.util.StopWatch

public class StopWatch
extends Object

Simple stop watch, allowing for timing of a number of tasks, exposing total running time and running time for each named task.

Conceals use of System.nanoTime(), improving the readability of application code and reducing the likelihood of calculation errors.

Note that this object is not designed to be thread-safe and does not use synchronization.

This class is normally used to verify performance during proof-of-concept work and in development, rather than as part of production applications.

Running time is tracked and reported in nanoseconds. As of Spring Framework 6.1, the default time unit for String renderings is seconds with decimal points in nanosecond precision. Custom renderings with specific time units can be requested through prettyPrint(TimeUnit).

Since:

May 2, 2001

Author:

Rod Johnson, Juergen Hoeller, Sam Brannen

See Also:

• start()
• stop()
• shortSummary()
• prettyPrint()

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	StopWatch.TaskInfo	Nested class to hold data about one task executed within the StopWatch.

Constructor Summary

Constructors

Constructor	Description
StopWatch()	Construct a new StopWatch.
StopWatch(String id)	Construct a new StopWatch with the given id.

Method Summary

Modifier and Type	Method	Description
@Nullable String	currentTaskName()	Get the name of the currently running task, if any.
String	getId()	Get the id of this StopWatch, as specified on construction.
StopWatch.TaskInfo	getLastTaskInfo()	Deprecated. as of 6.1, in favor of lastTaskInfo()
String	getLastTaskName()	Deprecated. as of 6.1, in favor of lastTaskInfo()
long	getLastTaskTimeMillis()	Deprecated. as of 6.1, in favor of lastTaskInfo()
long	getLastTaskTimeNanos()	Deprecated. as of 6.1, in favor of lastTaskInfo()
int	getTaskCount()	Get the number of tasks timed.
StopWatch.TaskInfo[]	getTaskInfo()	Get an array of the data for tasks performed.
double	getTotalTime(TimeUnit timeUnit)	Get the total time for all tasks in the requested time unit (with decimal points in nanosecond precision).
long	getTotalTimeMillis()	Get the total time for all tasks in milliseconds.
long	getTotalTimeNanos()	Get the total time for all tasks in nanoseconds.
double	getTotalTimeSeconds()	Get the total time for all tasks in seconds.
boolean	isRunning()	Determine whether this StopWatch is currently running.
StopWatch.TaskInfo	lastTaskInfo()	Get the last task as a StopWatch.TaskInfo object.
String	prettyPrint()	Generate a table describing all tasks performed in seconds (with decimal points in nanosecond precision).
String	prettyPrint(TimeUnit timeUnit)	Generate a table describing all tasks performed in the requested time unit (with decimal points in nanosecond precision).
void	setKeepTaskList(boolean keepTaskList)	Configure whether the StopWatch.TaskInfo array is built over time.
String	shortSummary()	Get a short description of the total running time in seconds.
void	start()	Start an unnamed task.
void	start(String taskName)	Start a named task.
void	stop()	Stop the current task.
String	toString()	Generate an informative string describing all tasks performed in seconds.

Methods inherited from class Object

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

Constructor Details

StopWatch

public StopWatch()

Construct a new StopWatch.

Does not start any task.

StopWatch

public StopWatch(String id)

Construct a new StopWatch with the given id.

The id is handy when we have output from multiple stop watches and need to distinguish between them.

Does not start any task.

Parameters:

id - identifier for this stop watch

Method Details

getId

public String getId()

Get the id of this StopWatch, as specified on construction.

Returns:

the id (empty String by default)

Since:

4.2.2

See Also:

• StopWatch(String)

setKeepTaskList

public void setKeepTaskList(boolean keepTaskList)

Configure whether the StopWatch.TaskInfo array is built over time.

Set this to false when using a StopWatch for millions of tasks; otherwise, the TaskInfo structure will consume excessive memory.

Default is true.

start

public void start()
           throws IllegalStateException

Start an unnamed task.

The results are undefined if stop() or timing methods are called without invoking this method first.

Throws:

IllegalStateException

See Also:

• start(String)
• stop()

start

public void start(String taskName)
           throws IllegalStateException

Start a named task.

The results are undefined if stop() or timing methods are called without invoking this method first.

Parameters:

taskName - the name of the task to start

Throws:

IllegalStateException

See Also:

• start()
• stop()

stop

public void stop()
          throws IllegalStateException

Stop the current task.

The results are undefined if timing methods are called without invoking at least one pair of start() / stop() methods.

Throws:

IllegalStateException

See Also:

• start()
• start(String)

isRunning

public boolean isRunning()

Determine whether this StopWatch is currently running.

See Also:

• currentTaskName()

currentTaskName

public @Nullable String currentTaskName()

Get the name of the currently running task, if any.

Since:

4.2.2

See Also:

• isRunning()

lastTaskInfo

public StopWatch.TaskInfo lastTaskInfo()
                                throws IllegalStateException

Get the last task as a StopWatch.TaskInfo object.

Throws:

IllegalStateException - if no tasks have run yet

Since:

6.1

getLastTaskInfo

@Deprecated(since="6.1")
public StopWatch.TaskInfo getLastTaskInfo()
                                   throws IllegalStateException

Deprecated.

as of 6.1, in favor of lastTaskInfo()

Get the last task as a StopWatch.TaskInfo object.

Throws:

IllegalStateException

getLastTaskName

@Deprecated(since="6.1")
public String getLastTaskName()
                       throws IllegalStateException

Deprecated.

as of 6.1, in favor of lastTaskInfo()

Get the name of the last task.

Throws:

IllegalStateException

See Also:

• StopWatch.TaskInfo.getTaskName()

getLastTaskTimeNanos

@Deprecated(since="6.1")
public long getLastTaskTimeNanos()
                          throws IllegalStateException

Deprecated.

as of 6.1, in favor of lastTaskInfo()

Get the time taken by the last task in nanoseconds.

Throws:

IllegalStateException

Since:

5.2

See Also:

• StopWatch.TaskInfo.getTimeNanos()

getLastTaskTimeMillis

@Deprecated(since="6.1")
public long getLastTaskTimeMillis()
                           throws IllegalStateException

Deprecated.

as of 6.1, in favor of lastTaskInfo()

Get the time taken by the last task in milliseconds.

Throws:

IllegalStateException

See Also:

• StopWatch.TaskInfo.getTimeMillis()

getTaskInfo

public StopWatch.TaskInfo[] getTaskInfo()

Get an array of the data for tasks performed.

See Also:

• setKeepTaskList(boolean)

getTaskCount

public int getTaskCount()

Get the number of tasks timed.

getTotalTimeNanos

public long getTotalTimeNanos()

Get the total time for all tasks in nanoseconds.

Since:

5.2

See Also:

• getTotalTime(TimeUnit)

getTotalTimeMillis

public long getTotalTimeMillis()

Get the total time for all tasks in milliseconds.

See Also:

• getTotalTime(TimeUnit)

getTotalTimeSeconds

public double getTotalTimeSeconds()

Get the total time for all tasks in seconds.

See Also:

• getTotalTime(TimeUnit)

getTotalTime

public double getTotalTime(TimeUnit timeUnit)

Get the total time for all tasks in the requested time unit (with decimal points in nanosecond precision).

Parameters:

timeUnit - the unit to use

Since:

6.1

See Also:

• getTotalTimeNanos()
• getTotalTimeMillis()
• getTotalTimeSeconds()

prettyPrint

public String prettyPrint()

Generate a table describing all tasks performed in seconds (with decimal points in nanosecond precision).

For custom reporting, call getTaskInfo() and use the data directly.

See Also:

• prettyPrint(TimeUnit)
• getTotalTimeSeconds()
• StopWatch.TaskInfo.getTimeSeconds()

prettyPrint

public String prettyPrint(TimeUnit timeUnit)

Generate a table describing all tasks performed in the requested time unit (with decimal points in nanosecond precision).

For custom reporting, call getTaskInfo() and use the data directly.

Parameters:

timeUnit - the unit to use for rendering total time and task time

Since:

6.1

See Also:

• prettyPrint()
• getTotalTime(TimeUnit)
• StopWatch.TaskInfo.getTime(TimeUnit)

shortSummary

public String shortSummary()

Get a short description of the total running time in seconds.

See Also:

• prettyPrint()
• prettyPrint(TimeUnit)

toString

public String toString()

Generate an informative string describing all tasks performed in seconds.

Overrides:

toString in class Object

See Also:

• prettyPrint()
• prettyPrint(TimeUnit)