How to implement stack in java by using array, a code by vasu

Stack is very important concept in computer science.

It is a liner data structure, that do supports a LIFO behavior (Last In First Out). This is widely used in IT industry. 

This very good code of stack is implemented by 

Vasu Gupta / IT / Maharaja Agrasen Institute of Technology

In this code the stack is implemented using array. I will also update stack implementation using linked list.

# save this class inside Stack.java file #

import java.util.Scanner;

// Create a class Stack consisting of main method in it

public class Stack {

// Declare some static variables

        // so they can be accessed from anywhere

static int max = 5 , top = -1 ;

static int[] stack = new int[max];

static int data = 0 ;

public static void main(String[] args) {

// Create Scanner class object

Scanner sc = new Scanner(System.in);

// Get user input data again and again

do {

System.out.print("Enter the data : ");

data = sc.nextInt();

push(data); // Push the data into the stack

System.out.print("Do you want to add more (y/n) : ");

}while(sc.next().equals("y"));

// Show the stack data : 

System.out.print("Stack : ");

showData();

// Pop the top element out of the stack

System.out.print("Poping one element out : ");

pop();

showData();

// Show the top element of the stack

peek();

}

//  method push() so that it can be accessed in the static main method

public static void push(int data) {

// Check if stack is full

if(top == max-1) {

System.out.println("Stack is Full");

}else { // Else push the data

top++ ;

stack[top] = data ;

}

}

// method pop()  to delete the top element in the stack

public static void pop() {

// Check if stack is empty

if(top == 0) {

System.out.println("Stack Empty");

}else { // Else pop the data

stack[top] = 0  ;

top-- ; 

}

}

// method peek() to fetch the top element from the stack

public static void peek() {

// Check if stack is empty

if(top == 0) {

System.out.println("Stack Empty");

}else { // Else print the top element of the stack

System.out.println("Top Element : " + stack[top]);

}

}

// method showData() to show the data of the stack

public static void showData() {

for (int i = 0; i < top; i++) { // Traverse until top

System.out.print(stack[i] + "-->");

}

System.out.println(stack[top]);

}

}