Stack Implementation in Java Using Array

In this post we’ll see an implementation of Stack in Java using array. Stack can also be implemented using Linked list.

• Refer Stack Implementation in Java Using Linked List to see how to implement Stack using Linked List in Java.

Stack data structure

A stack is a Last In First Out (LIFO) data structure. In a stack items are both inserted and removed from the top and you have access to a single data item; that is the last item inserted. Once that is retrieved then only you can access the next item.

Following image shows the items in a Stack.

Operations in a Stack

Mainly following three operations are implemented for a Stack-

1. push- To insert an item on the stack.
2. pop- To remove an item from the top of the stack.
3. peek- Read value from the top of the stack without removing it.

Java program for Stack

public class Stack {
  private int maxSize;
  private int[] stackArray;
  private int top;
  Stack(int max){
    this.maxSize = max;
    stackArray = new int[maxSize];
    top = -1;
  }
    
  public void push(int item){
    if(top >= maxSize - 1){
      System.out.println("Stack already full..");
      return;
    }
    // increment top then insert item
    stackArray[++top] = item;
  }
    
  public int pop(){
    if(top < 0){
      throw new RuntimeException("Stack is Empty");
    }
    // retrieve item then decrement
    return stackArray[top--];
  }
    
  public int peek(){
    // return top item value
    return stackArray[top];
  }
    
  public boolean isEmpty(){
    return (top < 0);
  }

  public boolean isFull(){
    return (top == maxSize - 1);
  }
    
  public static void main(String[] args) {
    Stack stack = new Stack(20);
    stack.push(1);
    stack.push(2);
    stack.push(3);
    stack.push(4);
    stack.push(5);
    System.out.println("Item popped- " + stack.pop());
    System.out.println("Item popped- " + stack.pop());
    while(!stack.isEmpty()){
      System.out.println("Item popped- " + stack.pop());
    }
  }
}

Output

Item popped- 5
Item peeked- 4
Item popped- 4
Item popped- 3
Item popped- 2
Item popped- 1

Performance of stack

In stack items can be inserted and removed in O(1) time.

That's all for this topic Stack Implementation in Java Using Array. If you have any doubt or any suggestions to make please drop a comment. Thanks!

>>>Return to Java Programs Page

---

Related Topics

1. Linked List Implementation Java Program
2. Binary Tree Traversal Using Depth First Search Java Program
3. Binary Search Program in Java
4. Heap Sort Program in Java
5. Check if Given String or Number is a Palindrome Java Program

You may also like-

1. How to Create Deadlock in Java
2. How to Create Password Protected Zip File in Java
3. How to Append to a File in Java
4. How to Display Pyramid Patterns in Java - Part2
5. Lock Striping in Java Concurrency
6. Thread Priority in Java Multi-Threading
7. String Comparison in Java equals(), compareTo(), startsWith() Methods
8. Spring Job Scheduling Using TaskScheduler And @Scheduled Annotation