Hi I am trying to implement an array based BT.Here is my code for this. But I'm stuck with Postorder traversal.
How can I get a Postorder traversal from my array based BT ?

My Entire code is given here.

package com.TreeLab;

public class Stack {
    private final int SIZE = 20;
    private String[] st;
    private int top;
    public Stack()           // constructor
       st = new String[SIZE];    // make array
       top = -1;
    public void push(String j)   // put item on stack
       { st[++top] = j; }
    public String pop()          // take item off stack
       { return st[top--]; }
    public String peek()         // peek at top of stack
       { return st[top]; }
    public boolean isEmpty()  // true if nothing on stack
       { return (top == -1); }

package com.TreeLab;

public class TreeBuilder {
    //String root = "";
    int root=0;
    public String [] arr = new String [20];

    public void createRoot(String data){

            arr[0] = data;

        root =0;


    public void setLeft(String data, int root){
        arr[(root*2)+1] = data;

    public String getLeft(int root){
        return arr[(root*2)+1];

    public void setRight(String data , int root){
        arr[(root*2)+2] = data;

    public String getRight(int root){
        return arr[(root*2)+2];

    public void printTree(){
            for(int i=0;i<20;i++){
                if(arr[i] !=null)

package com.TreeLab;

public class Test {
    public static void main(String[] args){
        TreeBuilder  TB = new TreeBuilder();
        TB.setLeft("B", 0);
        TB.setRight("C", 0);
        TB.setLeft("D", 1);
        TB.setRight("E", 1);
        TB.setLeft("P", 2);
        //TB.setRight(, root)

Are you looking for a design/algorithm
or do you have one and need help coding it in java?

@NormR1 I need coding in java and I haven't any design or algorithm on this.

You need a design/algorithm before you can write any code.

Please provide me a suitable algo that matches with my procedure of code(if possible).I'm trying to solve it using Stack but not successfull yet.

Sorry, I don't have any design for you.

i think you should go through linked list or treemap or hashmap in java.
It will be suited for your algorithm.
First design your algorithm then start your implementation.