File	Doc	Category	Size	Date	Package
Timer.java	API Doc	J2ME MIDP 2.0	24681	Thu Nov 07 12:02:26 GMT 2002	java.util

Timer

• java.lang.Object

Fields Summary
private TaskQueue	queue The timer task queue. This data structure is shared with the timer thread. The timer produces tasks, via its various schedule calls, and the timer thread consumes, executing timer tasks as appropriate, and removing them from the queue when they're obsolete.
private TimerThread	thread The timer thread.

Constructors Summary
public Timer() Creates a new timer. The associated thread does not run as a daemon thread, which may prevent an application from terminating. see Thread see #cancel() thread.start();

Methods Summary
public void	cancel() Terminates this timer, discarding any currently scheduled tasks. Does not interfere with a currently executing task (if it exists). Once a timer has been terminated, its execution thread terminates gracefully, and no more tasks may be scheduled on it. Note that calling this method from within the run method of a timer task that was invoked by this timer absolutely guarantees that the ongoing task execution is the last task execution that will ever be performed by this timer. This method may be called repeatedly; the second and subsequent calls have no effect. synchronized (queue) { thread.newTasksMayBeScheduled = false; queue.clear(); queue.notify(); // In case queue was already empty. }
private void	sched(java.util.TimerTask task, long time, long period) Schedule the specified timer task for execution at the specified time with the specified period, in milliseconds. If period is positive, the task is scheduled for repeated execution; if period is zero, the task is scheduled for one-time execution. Time is specified in Date.getTime() format. This method checks timer state, task state, and initial execution time, but not period. param task task to be scheduled. param time time at which task is to be executed. param period time in milliseconds between successive task executions. throws IllegalArgumentException if time() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. if (time < 0) throw new IllegalArgumentException("Illegal execution time."); synchronized (queue) { if (!thread.newTasksMayBeScheduled) { throw new IllegalStateException("Timer already cancelled."); } /* * If the TimerThread has exited without an error * it is restarted. See the commentary in TimerThread.run. */ if (!(thread.isAlive())) { thread = new TimerThread(queue); thread.start(); } synchronized (task.lock) { if (task.state != TimerTask.VIRGIN) { throw new IllegalStateException( "Task already scheduled or cancelled"); } task.nextExecutionTime = time; task.period = period; task.state = TimerTask.SCHEDULED; } queue.add(task); if (queue.getMin() == task) queue.notify(); }
public void	schedule(java.util.TimerTask task, long delay) Schedules the specified task for execution after the specified delay. param task task to be scheduled. param delay delay in milliseconds before task is to be executed. throws IllegalArgumentException if delay is negative, or delay + System.currentTimeMillis() is negative. throws IllegalStateException if task was already scheduled or cancelled, or timer was cancelled. if (delay < 0) throw new IllegalArgumentException("Negative delay."); sched(task, System.currentTimeMillis()+delay, 0);
public void	schedule(java.util.TimerTask task, java.util.Date time) Schedules the specified task for execution at the specified time. If the time is in the past, the task is scheduled for immediate execution. param task task to be scheduled. param time time at which task is to be executed. throws IllegalArgumentException if time.getTime() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. sched(task, time.getTime(), 0);
public void	schedule(java.util.TimerTask task, long delay, long period) Schedules the specified task for repeated fixed-delay execution, beginning after the specified delay. Subsequent executions take place at approximately regular intervals separated by the specified period. In fixed-delay execution, each execution is scheduled relative to the actual execution time of the previous execution. If an execution is delayed for any reason (such as garbage collection or other background activity), subsequent executions will be delayed as well. In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate). Fixed-delay execution is appropriate for recurring activities that require "smoothness." In other words, it is appropriate for activities where it is more important to keep the frequency accurate in the short run than in the long run. This includes most animation tasks, such as blinking a cursor at regular intervals. It also includes tasks wherein regular activity is performed in response to human input, such as automatically repeating a character as long as a key is held down. param task task to be scheduled. param delay delay in milliseconds before task is to be executed. param period time in milliseconds between successive task executions. throws IllegalArgumentException if delay is negative, or delay + System.currentTimeMillis() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. if (delay < 0) throw new IllegalArgumentException("Negative delay."); if (period <= 0) throw new IllegalArgumentException("Non-positive period."); sched(task, System.currentTimeMillis()+delay, -period);
public void	schedule(java.util.TimerTask task, java.util.Date firstTime, long period) Schedules the specified task for repeated fixed-delay execution, beginning at the specified time. Subsequent executions take place at approximately regular intervals, separated by the specified period. In fixed-delay execution, each execution is scheduled relative to the actual execution time of the previous execution. If an execution is delayed for any reason (such as garbage collection or other background activity), subsequent executions will be delayed as well. In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate). Fixed-delay execution is appropriate for recurring activities that require "smoothness." In other words, it is appropriate for activities where it is more important to keep the frequency accurate in the short run than in the long run. This includes most animation tasks, such as blinking a cursor at regular intervals. It also includes tasks wherein regular activity is performed in response to human input, such as automatically repeating a character as long as a key is held down. param task task to be scheduled. param firstTime First time at which task is to be executed. param period time in milliseconds between successive task executions. throws IllegalArgumentException if time.getTime() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. if (period <= 0) throw new IllegalArgumentException("Non-positive period."); sched(task, firstTime.getTime(), -period);
public void	scheduleAtFixedRate(java.util.TimerTask task, long delay, long period) Schedules the specified task for repeated fixed-rate execution, beginning after the specified delay. Subsequent executions take place at approximately regular intervals, separated by the specified period. In fixed-rate execution, each execution is scheduled relative to the scheduled execution time of the initial execution. If an execution is delayed for any reason (such as garbage collection or other background activity), two or more executions will occur in rapid succession to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate). Fixed-rate execution is appropriate for recurring activities that are sensitive to absolute time, such as ringing a chime every hour on the hour, or running scheduled maintenance every day at a particular time. It is also appropriate for for recurring activities where the total time to perform a fixed number of executions is important, such as a countdown timer that ticks once every second for ten seconds. Finally, fixed-rate execution is appropriate for scheduling multiple repeating timer tasks that must remain synchronized with respect to one another. param task task to be scheduled. param delay delay in milliseconds before task is to be executed. param period time in milliseconds between successive task executions. throws IllegalArgumentException if delay is negative, or delay + System.currentTimeMillis() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. if (delay < 0) throw new IllegalArgumentException("Negative delay."); if (period <= 0) throw new IllegalArgumentException("Non-positive period."); sched(task, System.currentTimeMillis()+delay, period);
public void	scheduleAtFixedRate(java.util.TimerTask task, java.util.Date firstTime, long period) Schedules the specified task for repeated fixed-rate execution, beginning at the specified time. Subsequent executions take place at approximately regular intervals, separated by the specified period. In fixed-rate execution, each execution is scheduled relative to the scheduled execution time of the initial execution. If an execution is delayed for any reason (such as garbage collection or other background activity), two or more executions will occur in rapid succession to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of the specified period (assuming the system clock underlying Object.wait(long) is accurate). Fixed-rate execution is appropriate for recurring activities that are sensitive to absolute time, such as ringing a chime every hour on the hour, or running scheduled maintenance every day at a particular time. It is also appropriate for for recurring activities where the total time to perform a fixed number of executions is important, such as a countdown timer that ticks once every second for ten seconds. Finally, fixed-rate execution is appropriate for scheduling multiple repeating timer tasks that must remain synchronized with respect to one another. param task task to be scheduled. param firstTime First time at which task is to be executed. param period time in milliseconds between successive task executions. throws IllegalArgumentException if time.getTime() is negative. throws IllegalStateException if task was already scheduled or cancelled, timer was cancelled, or timer thread terminated. if (period <= 0) throw new IllegalArgumentException("Non-positive period."); sched(task, firstTime.getTime(), period);