Timer

Class Overview

This class provides a very simple API for calling methods either once or repeatedly after a delay. Instead of creating objects of this class using the new keyword, you can use the following static "factory" methods to queue up delayed method calls in the background:

callOnce(Object receiver, String methodName, long delay)

Requests that an object's method be called once after a number of milliseconds has passed.

callRepeatedly(Object receiver, String methodName, long delay)

Requests that an object's method be called repeatedly after a number of milliseconds has passed.

callRepeatedly(Object receiver, String methodName, long initialDelay, long repeatDelay)

Requests that an object's method be called repeatedly, with separate controls over the initial delay (before the first call) and the repeat delay (between subsequent calls).

Each of these methods returns a Timer object, which can be stored and used later if necessary. For example, you may want to keep the timer in a field so that you can stop the repetition in response to a user action (like a button click) or some other external event.

Methods the timer can call

The method whose name is passed to these factory methods must be public, take no arguments, and return either void or boolean. Be careful: if a method with the correct name is found but the arguments do not match, then no error will be produced at runtime, and the method will simply not be called.

The version of the method that returns boolean is useful for timers created by callRepeatedly. In this case, returning true will cause the timer to stop (and the method will not be called again), or returning true will cause the timer to continue processing and fire again after the delay. If the method returns void instead, then the timer will run indefinitely, until it is stopped by calling stop().

Automatic lifecycle management

If the receiver for the timed method call is a Screen, then the timer will be automatically managed as part of the screen's lifecycle; the timer will be paused and resumed automatically during the screen's onPause and onResume methods, respectively.

If the method receiver is another object, then you will manually pause and resume the timer. Backing out of an activity or leaving the application does not automatically stop the timer, in most cases.

Threading concerns

Timed methods are called on the same thread that calls the factory method that starts the timer. In most cases, this is the GUI thread, and therefore it is safe to update the GUI from within a method called by a timer if the timer is started from the GUI thread.

If you are using the Timer class from another thread, it may be important to be aware that the method will be called on that same thread, not on the GUI thread.

Summary

[Expand] Inherited Methods
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)