Using the following implementation of Tree in java

class Node

{

public int iData; // data item (key)

public double dData; // data item

public Node leftChild; // this node's left child

public Node rightChild; // this node's right child

public void displayNode() // display ourself

{

System.out.print('{');

System.out.print(iData);

System.out.print(", ");

System.out.print(dData);

System.out.print("} ");

}

} // end class Node

//------------------------------------------------------------------

import java.io.IOException;

import java.util.Stack;

public class Tree

 {

 private Node root; // first node of tree

// -------------------------------------------------------------

 public Tree() // constructor

 { root = null; } // no nodes in tree yet

// -------------------------------------------------------------

 public Node find(int key) // find node with given key

 { // (assumes non-empty tree)

 Node current = root; // start at root

 while(current.iData != key) // while no match,

 {

 if(key < current.iData) // go left?

 current = current.leftChild;

 else // or go right?

 current = current.rightChild;

 if(current == null) // if no child,

 return null; // didn't find it

 }

 return current; // found it

 } // end find()

// -------------------------------------------------------------

 public void insert(int id, double dd)

 {

 Node newNode = new Node(); // make new node

 newNode.iData = id; // insert data

 newNode.dData = dd;

 if(root==null) // no node in root

 root = newNode;

 else // root occupied

 {

 Node current = root; // start at root

 Node parent;

 while(true) // (exits internally)

 {

 parent = current;

 if(id < current.iData) // go left?

 {

 current = current.leftChild;

 if(current == null) // if end of the line,

 { // insert on left

 parent.leftChild = newNode;

 return;

 }

 } // end if go left

 else // or go right?

 {

 current = current.rightChild;

 if(current == null) // if end of the line

 { // insert on right

 parent.rightChild = newNode;

 return;

 }

 } // end else go right

 } // end while

 } // end else not root

 } // end insert()

// -------------------------------------------------------------

 public boolean delete(int key) // delete node with given key

 { // (assumes non-empty list)

 Node current = root;

 Node parent = root;

 boolean isLeftChild = true;

 while(current.iData != key) // search for node

 {

 parent = current;

 if(key < current.iData) // go left?

 {

 isLeftChild = true;

 current = current.leftChild;

 }

 else // or go right?

 {

 isLeftChild = false;

 current = current.rightChild;

 }

 if(current == null) // end of the line,

 return false; // didn't find it

 } // end while

 // found node to delete

 // if no children, simply delete it

 if(current.leftChild==null &&

 current.rightChild==null)

 {

 if(current == root) // if root,

 root = null; // tree is empty

 else if(isLeftChild)

 parent.leftChild = null; // disconnect

 else // from parent

 parent.rightChild = null;

 }

 // if no right child, replace with left subtree

 else if(current.rightChild==null)

 if(current == root)

 root = current.leftChild;

 else if(isLeftChild)

 parent.leftChild = current.leftChild;

 else

 parent.rightChild = current.leftChild;

 // if no left child, replace with right subtree

 else if(current.leftChild==null)

 if(current == root)

 root = current.rightChild;

 else if(isLeftChild)

 parent.leftChild = current.rightChild;

 else

 parent.rightChild = current.rightChild;

 else // two children, so replace with inorder successor

 {

 // get successor of node to delete (current)

 Node successor = getSuccessor(current);

 // connect parent of current to successor instead

 if(current == root)

 root = successor;

 else if(isLeftChild)

 parent.leftChild = successor;

 else

 parent.rightChild = successor;

 // connect successor to current's left child

 successor.leftChild = current.leftChild;

 } // end else two children

 // (successor cannot have a left child)

 return true; // success

 } // end delete()

// -------------------------------------------------------------

 // returns node with next-highest value after delNode

 // goes to right child, then right child's left descendents

 private Node getSuccessor(Node delNode)

 {

 Node successorParent = delNode;

 Node successor = delNode;

 Node current = delNode.rightChild; // go to right child

 while(current != null) // until no more

 { // left children,

 successorParent = successor;

 successor = current;

 current = current.leftChild; // go to left child

 }

 // if successor not

 if(successor != delNode.rightChild) // right child,

 { // make connections

 successorParent.leftChild = successor.rightChild;

 successor.rightChild = delNode.rightChild;

 }

 return successor;

 }

// -------------------------------------------------------------

 public void traverse(int traverseType)

 {

 switch(traverseType)

 {

 case 1: System.out.print(" Preorder traversal: ");

 preOrder(root);

 break;

 case 2: System.out.print(" Inorder traversal: ");

 inOrder(root);

 break;

 case 3: System.out.print(" Postorder traversal: ");

 postOrder(root);

 break;

 }

 System.out.println();

 }

// -------------------------------------------------------------

 private void preOrder(Node localRoot)

 {

 if(localRoot != null)

 {

 System.out.print(localRoot.iData + " ");

 preOrder(localRoot.leftChild);

 preOrder(localRoot.rightChild);

 }

 }

// -------------------------------------------------------------

 private void inOrder(Node localRoot)

 {

 if(localRoot != null)

 {

 inOrder(localRoot.leftChild);

 System.out.print(localRoot.iData + " ");

 inOrder(localRoot.rightChild);

 }

 }

// -------------------------------------------------------------

 private void postOrder(Node localRoot)

 {

 if(localRoot != null)

 {

 postOrder(localRoot.leftChild);

 postOrder(localRoot.rightChild);

 System.out.print(localRoot.iData + " ");

 }

 }

// -------------------------------------------------------------

Add the following methods:

1- Implement in JAVA a method in class binary tree of integer to copy the tree in post-order into a singly linked list.

2- Implement in JAVA a recursive method to check that a binary tree of integer numbers is a heap.

3- Implement a JAVA method by adding attribute parent to each node in a binary tree, starting from an existing binary tree using in-order method, assign a reference to each parent of any node of the tree. Example the parent of the root is equal to null.

4- Implement in JAVA a method to calculate the sum of all values in a binary tree of integers.