Timed Iterator

Here is a quick tip for time constrained operations in java. If you need to process a long list but stop at some point in time, here is a solution:

import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Timer;
import java.util.TimerTask;
import java.util.concurrent.TimeUnit;

public class TimedIterator<T> implements Iterator<T> {

  private Iterator<T> originalIterator;
  protected boolean nowIsTheTime;
  private final TimerTask timerTask = new TimerTask() {
    @Override
    public void run() {
      TimedIterator.this.nowIsTheTime = true;
    }
  };

  public TimedIterator(Iterator<T> originalIterator, long duration, TimeUnit units) {
    this.originalIterator = originalIterator;
    Timer timer = new Timer();
    timer.schedule(this.timerTask, units.toMillis(duration));
  }

  @Override
  public boolean hasNext() {
    return this.originalIterator.hasNext() && !this.nowIsTheTime;
  }

  @Override
  public T next() {
    if (this.nowIsTheTime) {
      throw new NoSuchElementException();
    }
    return this.originalIterator.next();
  }

}

To use it, you can do something like this:

TimedIterator<Integer> it = new TimedIterator<>(testIterator, 1, TimeUnit.SECONDS);

where testIterator is an instance of any iterator implementing class.

This can also be used for streams:

Stream<Integer> stream = StreamSupport
        .stream(Spliterators.spliteratorUnknownSize(it, Spliterator.DISTINCT), false);