@Beta @GwtCompatible(emulated=true) public final class Stopwatch extends java.lang.Object
System.nanoTime()
for a few reasons:
nanoTime
, the value returned has no absolute
meaning, and can only be interpreted as relative to another timestamp
returned by nanoTime
at a different time. Stopwatch
is a
more effective abstraction because it exposes only these relative values,
not the absolute ones.
Basic usage:
Stopwatch stopwatch = Stopwatch.createStarted
(); doSomething(); stopwatch.stop
(); // optional long millis = stopwatch.elapsed(MILLISECONDS); log.info("time: " + stopwatch); // formatted string like "12.3 ms"
Stopwatch methods are not idempotent; it is an error to start or stop a stopwatch that is already in the desired state.
When testing code that uses this class, use
createUnstarted(Ticker)
or createStarted(Ticker)
to
supply a fake or mock ticker.
This allows you to
simulate any valid behavior of the stopwatch.
Note: This class is not thread-safe.
Modifier and Type | Field and Description |
---|---|
private long |
elapsedNanos |
private boolean |
isRunning |
private long |
startTick |
private Ticker |
ticker |
Constructor and Description |
---|
Stopwatch()
Deprecated.
Use
createUnstarted() instead. |
Stopwatch(Ticker ticker)
Deprecated.
Use
createUnstarted(Ticker) instead. |
Modifier and Type | Method and Description |
---|---|
private static java.lang.String |
abbreviate(java.util.concurrent.TimeUnit unit) |
private static java.util.concurrent.TimeUnit |
chooseUnit(long nanos) |
static Stopwatch |
createStarted()
Creates (and starts) a new stopwatch using
System.nanoTime()
as its time source. |
static Stopwatch |
createStarted(Ticker ticker)
Creates (and starts) a new stopwatch, using the specified time
source.
|
static Stopwatch |
createUnstarted()
Creates (but does not start) a new stopwatch using
System.nanoTime()
as its time source. |
static Stopwatch |
createUnstarted(Ticker ticker)
Creates (but does not start) a new stopwatch, using the specified time
source.
|
long |
elapsed(java.util.concurrent.TimeUnit desiredUnit)
Returns the current elapsed time shown on this stopwatch, expressed
in the desired time unit, with any fraction rounded down.
|
private long |
elapsedNanos() |
boolean |
isRunning()
|
Stopwatch |
reset()
Sets the elapsed time for this stopwatch to zero,
and places it in a stopped state.
|
Stopwatch |
start()
Starts the stopwatch.
|
Stopwatch |
stop()
Stops the stopwatch.
|
java.lang.String |
toString()
Returns a string representation of the current elapsed time.
|
private final Ticker ticker
private boolean isRunning
private long elapsedNanos
private long startTick
@Deprecated Stopwatch()
createUnstarted()
instead.System.nanoTime()
as its time source.@Deprecated Stopwatch(Ticker ticker)
createUnstarted(Ticker)
instead.public static Stopwatch createUnstarted()
System.nanoTime()
as its time source.public static Stopwatch createUnstarted(Ticker ticker)
public static Stopwatch createStarted()
System.nanoTime()
as its time source.public static Stopwatch createStarted(Ticker ticker)
public boolean isRunning()
public Stopwatch start()
Stopwatch
instancejava.lang.IllegalStateException
- if the stopwatch is already running.public Stopwatch stop()
Stopwatch
instancejava.lang.IllegalStateException
- if the stopwatch is already stopped.public Stopwatch reset()
Stopwatch
instanceprivate long elapsedNanos()
public long elapsed(java.util.concurrent.TimeUnit desiredUnit)
Note that the overhead of measurement can be more than a microsecond, so
it is generally not useful to specify TimeUnit.NANOSECONDS
precision here.
elapsedTime()
)@GwtIncompatible(value="String.format()") public java.lang.String toString()
toString
in class java.lang.Object
private static java.util.concurrent.TimeUnit chooseUnit(long nanos)
private static java.lang.String abbreviate(java.util.concurrent.TimeUnit unit)