Question

Class A 
{
 long x;
 method1()
  {
   x = current time in millisecs;
  }
 task()//want to run this after (x+30) time
}

I need to run task() after (x+30) . x could be varying. if method1 is called, then task is scheduled to run after 30 from current time, but within that 30 timeperiod if method1 is called again then i want to cancel the previous task call and want to schedule a new call to task after 30 sec from current time. How should i create a scheduler or task of this type?

Went through the scheduledthreadpoolexecutor API but didn’t find a scheduler of this type.

Answer 1

You’re asking 2 questions:

1. How can I schedule a task with an arbitrary delay?

You can use one of the schedule methods on a java.util.concurrent.ScheduledThreadPoolExecutor

int delay = System.currentTimeMillis + 30;
myScheduledExecutor.schedule(myTask, delay, TimeUnit.MILLISECONDS);

2. How can I cancel an already running task?

You cancel a task by calling cancel on the Future that is returned from the schedule method you called.

if (!future.isDone()){
    future.cancel(true);
}
future = myScheduledExecutor.schedule(myTask, delay, TimeUnit.MILLISECONDS);