Timers schedule one-shot or recurring Java.Util.TimerTask for execution. Prefer Java.Util.Concurrent.ScheduledThreadPoolExecutor for new code.

Each timer has one thread on which tasks are executed sequentially. When this thread is busy running a task, runnable tasks may be subject to delays.

One-shot are scheduled to run at an absolute time or after a relative delay.

Recurring tasks are scheduled with either a fixed period or a fixed rate:

• With the default fixed-period execution, each successive run of a task is scheduled relative to the start time of the previous run, so two runs are never fired closer together in time than the specified period.
• With fixed-rate execution, the start time of each successive run of a task is scheduled without regard for when the previous run took place. This may result in a series of bunched-up runs (one launched immediately after another) if delays prevent the timer from starting tasks on time.

When a timer is no longer needed, users should call Timer.Cancel, which releases the timer's thread and other resources. Timers not explicitly cancelled may hold resources indefinitely.

This class does not offer guarantees about the real-time nature of task scheduling. Multiple threads can share a single timer without synchronization.

[Android Documentation]