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| java.lang.Object
 java.util.TimerTask
| TimerTask | | abstract public class TimerTask implements Runnable(Code) | | A task that can be scheduled for one-time or repeated execution by a Timer.
author:
Josh Bloch
version:
1.17, 05/05/07
See Also: Timer
since:
1.3 |
| Field Summary | |
| final static int | CANCELLED
This task has been cancelled (with a call to TimerTask.cancel). | | final static int | EXECUTED
This non-repeating task has already executed (or is currently
executing) and has not been cancelled. | | final static int | SCHEDULED
This task is scheduled for execution. | | final static int | VIRGIN
This task has not yet been scheduled. | | final Object | lock
This object is used to control access to the TimerTask internals. | | long | nextExecutionTime
Next execution time for this task in the format returned by
System.currentTimeMillis, assuming this task is scheduled for execution. | | long | period
Period in milliseconds for repeating tasks. | | int | state
The state of this task, chosen from the constants below. |
| Constructor Summary | |
| protected | TimerTask()
Creates a new timer task. |
| Method Summary | |
| public boolean | cancel()
Cancels this timer task. | | abstract public void | run()
The action to be performed by this timer task. | | public long | scheduledExecutionTime()
Returns the scheduled execution time of the most recent
actual execution of this task. |
| CANCELLED | | final static int CANCELLED(Code) | | This task has been cancelled (with a call to TimerTask.cancel).
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| EXECUTED | | final static int EXECUTED(Code) | | This non-repeating task has already executed (or is currently
executing) and has not been cancelled.
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| SCHEDULED | | final static int SCHEDULED(Code) | | This task is scheduled for execution. If it is a non-repeating task,
it has not yet been executed.
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| VIRGIN | | final static int VIRGIN(Code) | | This task has not yet been scheduled.
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| lock | | final Object lock(Code) | | This object is used to control access to the TimerTask internals.
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| nextExecutionTime | | long nextExecutionTime(Code) | | Next execution time for this task in the format returned by
System.currentTimeMillis, assuming this task is scheduled for execution.
For repeating tasks, this field is updated prior to each task execution.
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| period | | long period(Code) | | 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.
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| state | | int state(Code) | | The state of this task, chosen from the constants below.
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| TimerTask | | protected TimerTask()(Code) | | Creates a new timer task.
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| cancel | | public boolean cancel()(Code) | | 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.
true if this task is scheduled for one-time execution and hasnot yet run, or this task is scheduled for repeated execution.Returns false if the task was scheduled for one-time executionand has already run, or if the task was never scheduled, or ifthe task was already cancelled. (Loosely speaking, this methodreturns true if it prevents one or more scheduledexecutions from taking place.) |
| run | | abstract public void run()(Code) | | The action to be performed by this timer task.
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| scheduledExecutionTime | | public long scheduledExecutionTime()(Code) | | 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.
the time at which the most recent execution of this task wasscheduled to occur, in the format returned by Date.getTime().The return value is undefined if the task has yet to commenceits first execution.
See Also: Date.getTime |
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