Is there a PriorityQueue implementation with fixed capacity and custom comparator?

Question

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Answer 1

Try this code:

public class BoundedPQueue> {
/**
 * Lock used for all public operations
 */
private final ReentrantLock lock;

PriorityBlockingQueue queue ;
int size = 0;

public BoundedPQueue(int capacity){
    queue = new PriorityBlockingQueue(capacity, new CustomComparator());
    size = capacity;
    this.lock = new ReentrantLock();

}

public boolean offer(E e) {


    final ReentrantLock lock = this.lock;
    lock.lock();
    E vl = null;
    if(queue.size()>= size)  {
        vl= queue.poll();
        if(vl.compareTo(e)<0)
            e=vl;
    }

    try {
        return queue.offer(e);
    } finally {
        lock.unlock();
    }


}

public E poll()  {

    return queue.poll();
}

public static class CustomComparator> implements Comparator {


    @Override
    public int compare(E o1, E o2) {
        //give me a max heap
         return o1.compareTo(o2) *-1;

    }
}

}