Priority Queue implementation for PuzzeBoard in Puzzle8 game

PuzzleBoardPriorityQueue.java

package com.google.engedu.puzzle8;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.NoSuchElementException;

/**
 * Created by Rohan on 11/27/2015.
 */
public class PuzzleBoardPriorityQueue {
    private ArrayList<PuzzleBoard> minHeap;


    public PuzzleBoardPriorityQueue(){
        minHeap = new ArrayList<>();

    }

    public PuzzleBoard minValue() {
        if (minHeap.size() == 0) {
            throw new NoSuchElementException();
        }
        return minHeap.get(0);
    }


    public void remove() {
        PuzzleBoard newValue = minHeap.remove(minHeap.size()-1);
        int pos = 0;
        if (minHeap.size() > 0) {
            while (2*pos+1 < minHeap.size()) {
                int minChild = 2*pos+1;
                if (2*pos+2 < minHeap.size() &&
                        minHeap.get(2*pos+2).priority() < minHeap.get(2*pos+1).priority()) {
                    minChild = 2 * pos +2;
                }

                if (newValue.priority() > minHeap.get(minChild).priority()) {
                    minHeap.set(pos, minHeap.get(minChild));
                    pos = minChild;
                }
                else {
                    break;
                }
            }
            minHeap.set(pos, newValue);
        }
    }

    public void addAll(ArrayList<PuzzleBoard> boards){
        for(PuzzleBoard board:boards){
            add(board);
        }
    }

    public void add(PuzzleBoard puzzleBoard){
        minHeap.add(puzzleBoard);
        int pos = minHeap.size()-1;

        while (pos > 0) {
            if (puzzleBoard.priority() < minHeap.get((pos-1)/2).priority()) {
                minHeap.set(pos, minHeap.get((pos-1)/2));
                pos = (pos-1)/2;
            }
            else {
                break;
            }
        }
        minHeap.set(pos, puzzleBoard);

    }

    public boolean isEmpty(){
        return minHeap.size() <= 0;
    }

    public PuzzleBoard poll(){
        PuzzleBoard min = null;
        if(!isEmpty()){
            min = minValue();
            remove();
        }
        return min;
    }


}