Making a boolean true for x seconds when condition is met, then reverting it to false

Question

I'm making a boolean so if a certain condition is met, it will return true for 3 seconds, but after that it will return false again.

So it's like

private boolean timedBoolean() {

         if(//condition to set boolean true){ 
            return true;
         }

        //if condition isn't met for 3 seconds
         return false;
     }

Been thinking about this for an hour now. Researched SO before I asked.

Answer 1

Remember the moment at which your 3-second period started:

private volatile long start;

and have the method check the elapsed time:

private boolean timedBoolean() {
    if (conditionMet()) {
      start = System.nanoTime();
      return true;
    }
    return System.nanoTime()-start < TimeUnit.SECONDS.toNanos(3);
}