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Switching between classes in Java?

I want to create a class for a heap data structure in Java that allows the user to choose MinHeap or MaxHeap

the constructor should look like this:

public Heap(String type) {
    if (type.equals("min")) {
        //allow this object only to use methods for MinHeap
    } else {
        //allow this object only to use methods for MaxHeap
    }
}

Note that the methods do differ from the two types. For example, this method is used in MaxHeaps and will not be implemented in the same way in MinHeap:

 public void maxHeapify(int i, int n) {
       int l = leftPos(i);
       int r = rightPos(i);
       int largest;
       if (l < n && heap.get(l) > heap.get(i)) {
           largest = l;
       } else {
           largest = i;
       }
       if (r < n && heap.get(r) > heap.get(largest)) {
           largest = r;
       }
       if (largest != i) {
           swap(i, largest);
           maxHeapify(largest, n);
        }
    }

I am using an array to represent MaxHeap.

Is it possible? Or should I make separate classes for MaxHeap and MinHeap; each with their own specific methods? or do you think I should follow this example: Example:

 public void getMax() {
      if (type.equals("min")) {
            //use the method for MinHeap
      } else {
           //apply the method for MaxHeap
      }
 }

Feel free to change the title of the question, because I didn't know exactly how to ask it

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2 answers


You must have an interface Heap

with two implementing classes - MinHeap

and MaxHeap

. This is how the Collections API is designed. For example, an interface List

has many implementations, some of which include LinkedList

and ArrayList

.



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You can implement it with a single class similar to the way java.util.PriorityQueue

. You can switch the priority by passing the appropriate comparator class.

This is similar to the constructor PriorityQueue(int initialCapacity, Comparator<? super E> comparator)

as described in the Javadocs:



Creates a PriorityQueue with the specified initial cardinality that orders its elements according to the specified comparator.

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