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TimerTask.javaAPI DocphoneME MR2 API (J2ME)5712Wed May 02 18:00:10 BST 2007java.util

TimerTask

public abstract class TimerTask extends Object implements Runnable
A task that can be scheduled for one-time or repeated execution by a Timer.
version
1.5, 12/04/99
see
Timer
since
1.3

Fields Summary
final Object
lock
This object is used to control access to the TimerTask internals.
int
state
The state of this task, chosen from the constants below.
static final int
VIRGIN
This task has not yet been scheduled.
static final int
SCHEDULED
This task is scheduled for execution. If it is a non-repeating task, it has not yet been executed.
static final int
EXECUTED
This non-repeating task has already executed (or is currently executing) and has not been cancelled.
static final int
CANCELLED
This task has been cancelled (with a call to TimerTask.cancel).
long
nextExecutionTime
Next execution time for this task in the format returned by System.currentTimeMillis, assuming this task is schedule for execution. For repeating tasks, this field is updated prior to each task execution.
long
period
Period in milliseconds for repeating tasks. A positive value indicates fixed-rate execution. A negative value indicates fixed-delay execution. A value of 0 indicates a non-repeating task.
Constructors Summary
protected TimerTask()
Creates a new timer task.
Methods Summary
public booleancancel()
Cancels this timer task. If the task has been scheduled for one-time execution and has not yet run, or has not yet been scheduled, it will never run. If the task has been scheduled for repeated execution, it will never run again. (If the task is running when this call occurs, the task will run to completion, but will never run again.)

Note that calling this method from within the run method of a repeating timer task absolutely guarantees that the timer task will not run again.

This method may be called repeatedly; the second and subsequent calls have no effect.

return
true if this task is scheduled for one-time execution and has not yet run, or this task is scheduled for repeated execution. Returns false if the task was scheduled for one-time execution and has already run, or if the task was never scheduled, or if the task was already cancelled. (Loosely speaking, this method returns true if it prevents one or more scheduled executions from taking place.)

        synchronized (lock) {
            boolean result = (state == SCHEDULED);
            state = CANCELLED;
            return result;
        }
public abstract voidrun()
The action to be performed by this timer task.

public longscheduledExecutionTime()
Returns the scheduled execution time of the most recent
actual execution of this task. (If this method is invoked
while task execution is in progress, the return value is the scheduled
execution time of the ongoing task execution.)


This method is typically invoked from within a task's run method, to
determine whether the current execution of the task is sufficiently
timely to warrant performing the scheduled activity:

public void run() {
if (System.currentTimeMillis() - scheduledExecutionTime() >=
MAX_TARDINESS)
return; // Too late; skip this execution.
// Perform the task
}


This method is typically not used in conjunction with
fixed-delay execution repeating tasks, as their scheduled
execution times are allowed to drift over time, and so are not terribly
significant.
return
the time at which the most recent execution of this task was
scheduled to occur, in the format returned by Date.getTime().
The return value is undefined if the task has yet to commence
its first execution.
see
Date#getTime()
        synchronized (lock) {
            return (period < 0 ? nextExecutionTime + period
                               : nextExecutionTime - period);
        }