Java Code:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


public class Heap {
  private Node[] heapArray;

  private int maxSize; // size of array

  private int currentSize; // number of nodes in array

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

  public boolean isEmpty() {
    return currentSize == 0;
  }

  public boolean insert(int key) {
    if (currentSize == maxSize)
      return false;
    Node newNode = new Node(key);
    heapArray[currentSize] = newNode;
    trickleUp(currentSize++);
    return true;
  } 

  public void trickleUp(int index) {
    int parent = (index - 1) / 2;
    Node bottom = heapArray[index];

    while (index > 0 && heapArray[parent].getKey() < bottom.getKey()) {
      heapArray[index] = heapArray[parent]; // move it down
      index = parent;
      parent = (parent - 1) / 2;
    }
    heapArray[index] = bottom;
  }

  public Node remove() // delete item with max key
  { // (assumes non-empty list)
    Node root = heapArray[0];
    heapArray[0] = heapArray[--currentSize];
    trickleDown(0);
    return root;
  } // end remove()

  public void trickleDown(int index) {
    int largerChild;
    Node top = heapArray[index]; // save root
    while (index < currentSize / 2) // while node has at
    { //    least one child,
      int leftChild = 2 * index + 1;
      int rightChild = leftChild + 1;
      // find larger child
      if (rightChild < currentSize
          && // (rightChild exists?)
          heapArray[leftChild].getKey() < heapArray[rightChild]
              .getKey())
        largerChild = rightChild;
      else
        largerChild = leftChild;
      // top >= largerChild?
      if (top.getKey() >= heapArray[largerChild].getKey())
        break;
      // shift child up
      heapArray[index] = heapArray[largerChild];
      index = largerChild; // go down
    }
    heapArray[index] = top; // root to index
  }

  public boolean change(int index, int newValue) {
    if (index < 0 || index >= currentSize)
      return false;
    int oldValue = heapArray[index].getKey(); // remember old
    heapArray[index].setKey(newValue); // change to new

    if (oldValue < newValue) 
      trickleUp(index); 
    else
      trickleDown(index);
    return true;
  }

  public void displayHeap() {
    System.out.print("heapArray: "); // array format
    for (int m = 0; m < currentSize; m++)
      if (heapArray[m] != null)
        System.out.print(heapArray[m].getKey() + " ");
      else
        System.out.print("-- ");
    int nBlanks = 32;
    int itemsPerRow = 1;
    int column = 0;
    int j = 0; // current item

    while (currentSize > 0) // for each heap item
    {
      if (column == 0) // first item in row?
        for (int k = 0; k < nBlanks; k++)
          // preceding blanks
          System.out.print(' ');
      // display item
      System.out.print(heapArray[j].getKey());

      if (++j == currentSize) // done?
        break;

      if (++column == itemsPerRow) // end of row?
      {
        nBlanks /= 2; // half the blanks
        itemsPerRow *= 2; // twice the items
        column = 0; // start over on
        System.out.println(); //    new row
      } else
        // next item on row
        for (int k = 0; k < nBlanks * 2 - 2; k++)
          System.out.print(' '); // interim blanks
    } 
  }

  public static void main(String[] args) throws IOException {
    int value, value2;
    Heap h = new Heap(31); // make a Heap; max size 31
    boolean success;

    h.insert(70); // insert 10 items
    h.insert(40);
    h.insert(50);
    h.insert(20);
    h.insert(60);
    h.insert(100);
    h.insert(80);
    h.insert(30);
    h.insert(10);
    h.insert(90);

    h.displayHeap();
    value = 100;
    success = h.insert(value);
    if (!success)
      System.out.println("Can't insert; heap full");
    if (!h.isEmpty())
      h.remove();
    else
      System.out.println("Can't remove; heap empty");
    value = 80;
    value2 = 999;
    success = h.change(value, value2);
    if (!success)
      System.out.println("Invalid index");
  }
  class Node {
    private int data; 

    public Node(int key) {
      data = key;
    }

    public int getKey() {
      return data;
    }

    public void setKey(int id) {
      data = id;
    }

  }

}