Android Guides | Samples

Android.OS.SystemClock Class

Core timekeeping facilities.

See Also: SystemClock

Syntax

[Android.Runtime.Register("android/os/SystemClock", DoNotGenerateAcw=true)]
public sealed class SystemClock : Object

Remarks

Core timekeeping facilities.

Three different clocks are available, and they should not be confused:

  • JavaSystem.CurrentTimeMillis is the standard "wall" clock (time and date) expressing milliseconds since the epoch. The wall clock can be set by the user or the phone network (see SystemClock.SetCurrentTimeMillis(Int64)), so the time may jump backwards or forwards unpredictably. This clock should only be used when correspondence with real-world dates and times is important, such as in a calendar or alarm clock application. Interval or elapsed time measurements should use a different clock. If you are using System.currentTimeMillis(), consider listening to the Intent.ActionTimeTick, Intent.ActionTimeChanged and Intent.ActionTimezoneChangedIntent broadcasts to find out when the time changes.
  • SystemClock.UptimeMillis is counted in milliseconds since the system was booted. This clock stops when the system enters deep sleep (CPU off, display dark, device waiting for external input), but is not affected by clock scaling, idle, or other power saving mechanisms. This is the basis for most interval timing such as Thread.Sleep(Int64), Object.Wait(Int64), and JavaSystem.NanoTime. This clock is guaranteed to be monotonic, and is suitable for interval timing when the interval does not span device sleep. Most methods that accept a timestamp value currently expect the SystemClock.UptimeMillis clock.
  • SystemClock.ElapsedRealtime and SystemClock.ElapsedRealtimeNanos return the time since the system was booted, and include deep sleep. This clock is guaranteed to be monotonic, and continues to tick even when the CPU is in power saving modes, so is the recommend basis for general purpose interval timing.
There are several mechanisms for controlling the timing of events:

[Android Documentation]

Requirements

Namespace: Android.OS
Assembly: Mono.Android (in Mono.Android.dll)
Assembly Versions: 0.0.0.0
Since: Added in API level 1

The members of Android.OS.SystemClock are listed below.

See Also: Object

Protected Properties

[read-only]
override
ThresholdClassIntPtr. This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.
[read-only]
override
ThresholdTypeType. This API supports the Mono for Android infrastructure and is not intended to be used directly from your code.

Public Methods

static
CurrentThreadTimeMillis() : Int64
Returns milliseconds running in the current thread.
static
ElapsedRealtime() : Int64
Returns milliseconds since boot, including time spent in sleep.
static
ElapsedRealtimeNanos() : Int64
Returns nanoseconds since boot, including time spent in sleep.
static
SetCurrentTimeMillis(Int64) : Boolean
Sets the current wall time, in milliseconds.
static
Sleep(Int64)
Waits a given number of milliseconds (of uptimeMillis) before returning.
static
UptimeMillis() : Int64
Returns milliseconds since boot, not counting time spent in deep sleep.