Heap Sort Implementation in Java

public class Main {
  public static void main(String[] args) {
    int size, i;//from   w ww.j a va2s  .com
    size = 10;
    Heap theHeap = new Heap(size);

    for (i = 0; i < size; i++) {
      int random = (int) (java.lang.Math.random() * 100);
      int newNode = random;
      theHeap.insertAt(i, newNode);
      theHeap.incrementSize();
    }

    System.out.print("Random: ");
    theHeap.displayArray();
    for (i = size / 2 - 1; i >= 0; i--)
      theHeap.sort(i);

    System.out.println("Heap:   ");
    theHeap.displayArray();
    theHeap.displayHeap();
    for (i = size - 1; i >= 0; i--) {
      int biggestNode = theHeap.remove();
      theHeap.insertAt(i, biggestNode);
    }
    System.out.println("Sorted: ");
    theHeap.displayArray();
  }

}

class Heap {
  private int[] heapArray;

  private int maxSize;

  private int currentSize; // number of items in array

  public Heap(int mx) {
    maxSize = mx;
    currentSize = 0;
    heapArray = new int[maxSize];
  }

  public int remove() {
    int root = heapArray[0];
    heapArray[0] = heapArray[--currentSize];
    sort(0);
    return root;
  }

  public void sort(int index) {
    int largerChild;
    int top = heapArray[index];
    while (index < currentSize / 2) {
      int leftChild = 2 * index + 1;
      int rightChild = leftChild + 1;
      // find larger child
      if (rightChild < currentSize
          && heapArray[leftChild] < heapArray[rightChild]) {
        largerChild = rightChild;
      } else {
        largerChild = leftChild;
      }
      if (top >= heapArray[largerChild]) {
        break;
      }
      heapArray[index] = heapArray[largerChild];
      index = largerChild;
    }
    heapArray[index] = top;
  }

  public void displayHeap() {
    int nBlanks = 32;
    int itemsPerRow = 1;
    int column = 0;
    int currentIndex = 0;
    while (currentSize > 0) {
      if (column == 0)
        for (int k = 0; k < nBlanks; k++){
          System.out.print(' ');
        }
      System.out.print(heapArray[currentIndex]);

      if (++currentIndex == currentSize){ // done?
        break;
      }
      if (++column == itemsPerRow) // end of row?
      {
        nBlanks /= 2;
        itemsPerRow *= 2;
        column = 0;
        System.out.println();
      } else{
        for (int k = 0; k < nBlanks * 2 - 2; k++){
          System.out.print(' '); // interim blanks
        }
      }
    }
    System.out.println();
  }

  public void displayArray() {
    for (int j = 0; j < maxSize; j++)
      System.out.println(heapArray[j]);
  }

  public void insertAt(int index, int newNode) {
    heapArray[index] = newNode;
  }

  public void incrementSize() {
    currentSize++;
  }

}