public void clear() {
        size = 0;
        first = new SortedBin(4, this);
        second = new SortedBin(4, this);
        firstNonEmpty = null;
    }
add a key value pair to the heap

@param key   the key to insert
@param value the value to insert object
main/src/main/java/cgeo/geocaching/brouter/util/SortedHeap.java