A Stack Class

By: aathishankaran Emailed: 1768 times Printed: 2515 times    

Latest comments
By: rohit kumar - how this program is work
By: Kirti - Hi..thx for the hadoop in
By: Spijker - I have altered the code a
By: ali mohammed - why we use the java in ne
By: ali mohammed - why we use the java in ne
By: mizhelle - when I exported the data
By: raul - no output as well, i'm ge
By: Rajesh - thanx very much...
By: Suindu De - Suppose we are executing

To show the real power of classes, this article will conclude with a more sophisticated example. One of OOP’s most important benefits is the encapsulation of data and the code that manipulates that data. As you have seen, the class, you are creating a new data type that defines both the nature of the data being manipulated and the routines used to manipulate it.


Further, the methods define a consistent and controlled interface to the class data. Thus, you can use the class through its methods without having to worry about the details of its implementation or how the data is actually managed within the class. In a sense, a class is like a “data engine.” No knowledge of what goes on inside the engine is required to use the engine through its controls. In fact, since the details are hidden, its inner workings can be changed as needed. As long as your code uses the class through its methods, internal details can change without causing side effects outside the class.


class Stack {

     int stck[] = new int[10];

     int tos;


stack() {

     tos = -1;



void push (int item) {

     if ( tos == 9)

          System.out.println(“Stack is full.”);


          stck[++tos] = item;



int pop() {

     if(tos < 0) {

          system.out.println(“Stack underflaow.”);

          return 0;



          return stck[tos--];




            As you can see, the Stack class defines two data items and three methods. The stack of integers is held by the array stck. This array is indexed by the variable tos, which always contains the index of the top of the stack. The Stack() constructor initializes tos to -1, which indicates an empty stack. The method push() puts and item on the stack. To retrieve an item, call pop(). Since access to the stack is through push() and pop(), the fact that the stack is held in an array is actually not relevant to using the stack. For example, the stack could be held in a more complicated data structure, such as a linked list, yet the interface defined by push() and pop() would remain the same.


            The class TestStack, shown here, demonstrates the Stack class. It creates two integer stacks, pushes some values onto each, and then pops them off.


Class TestStack {

     public static void main ( String args[]) {

          Stack mystack1 = new Stack();


     for (int i=0; i<10; i++) mystack1.push(i);


     System.out.println(“Stack in mystack1:”);

     for (int i=0; i<10; i++)





This program generates the following output:


Stack in mystack1:












As you can see, the contents of each stack are separate.


            One last point about the Stack class, as it is currently implemented; it is possible for the array that holds the stack, stck, to be altered by code outside of the Stack class. This leaves Stack open to misuse or mischief.

Java Home | All Java Tutorials | Latest Java Tutorials

Sponsored Links

If this tutorial doesn't answer your question, or you have a specific question, just ask an expert here. Post your question to get a direct answer.

Bookmark and Share


Be the first one to add a comment

Your name (required):

Your email(required, will not be shown to the public):

Your sites URL (optional):

Your comments:

More Tutorials by aathishankaran
Web Security Issues
The Web User's Perspective
Server-side plug-Ins
The best way to avoid security vulnerabilities with new server
JavaScript Security
Window Object
Working with Status Bar Messages
Retrieving a Portion of a String
Referencing Windows
Math Object
Frame Object
Document Object
Closing Windows
Built-in Object in Javascript
Textarea Object

More Tutorials in Java
Update contents of a file within a jar file
Tomcat and httpd configured in port 8080 and 80
Java File
Java String
Count number of vowels, consonants and digits in a String in Java
Reverse a number in Java
Student marks calculation program in Java
Handling Fractions in Java
Calculate gross salary in Java
Calculate average sale of the week in Java
Vector in Java - Sample Program
MultiLevel Inheritance sample in Java
Multiple Inheritance sample in Java
Java program using Method Overriding
Java program to check if user input is an even number

More Latest News
Most Viewed Articles (in Java )
InetAddress Example program in Java
Read from a COM port using Java program
Stack example in Java - push(), pop(), empty(), search()
How to use ArrayList in Java
The Basic Structure of a Simple Java program
Using StringTokenizer in Java
FileReader and FileWriter example program in Java
Transient vs Volatile modifiers in Java
Vector example in Java
Method Overriding in Java
Method Overloading (function overloading) in Java
instanceof sample program in Java
append() in Java
Student marks calculation program in Java
Reading from a file and writing to a file using Java program
Most Emailed Articles (in Java)
Text to Speech conversion program in Java
inheritance in Java
How to initialize an Array and how to copy the array
Using Charts in JasperReports
What is Unicode?
Operator Precedence in Java
Of Object, equals (), == and hashCode ()
DateFormat sample program in Java
A Simple whois program in Java
PushbackReader sample program in Java
CharArrayReader example program in Java
ByteArrayOutputStream - sample program in Java
Vector example in Java
Arrays example in Java - asList(), binarySearch(), fill(), sort(), equals()
HashSet Sample program in Java