Binary Tree in java(Generic)

Please help me.I want to make a binary tree in java.I started but
couldnot accomplish.Can anyone help me to complete .Reply soon
please.My Program is:-

import java.io.*;

interface Node {
          T getData();
          int getId();
   }

interface BinTree<T> {
          Node getLeft (Node n);
          Node getRight (Node n);
          Node[] leaves();
          Node parent(Node n);
          int numOfChildren(Node n);
}

class ArrayBinTree<T> implements BinTree<T> {
          class ArrayBinTreeNode<T> implements Node {
                T data;
                int id;
                T getData {return data;}
                int getId {return id;}

}

        ArrayBinTreeNode () { //default constructor
               id = 0;
               data = null;
          }
 ArrayBinTree (int s){ //copy constructor
               id = s;
               data = null;
           }

Node[] tree;
int numOfNodes;
BinTree(int size) {
tree = new Node[size];
numOfNodes = 0;
}

Node getLeft(Node n) {
return tree [2*n.getId()+1];
}

Node getRight(Node n) {
return tree [2*n.getId()+2];
}