How to Implement a Stack in Java Using Array [2023]

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Are you looking to implement a stack in Java using an array? Our team of expert developers at Stack Interface™ has extensive experience in implementing a stack using an array in Java. In this article, we will guide you through the process of implementing a stack in Java using an array. We will cover the basics of stacks, the implementation of stacks using an array, and the advantages and disadvantages of using an array in stack implementation.

What is a Stack?

Before we dive in, let's start with the basics. A stack is an abstract data type that follows the Last In First Out (LIFO) principle. In simple terms, the last element added to the stack will be the first one removed. Think of a stack of books on a desk, each book added to the stack goes on top of the previous book and the last book added will be the first one removed.

Stack Implementation Using an Array

Stacks can be implemented using an array in Java. Here is an example code snippet to get you started:

public class Stack {
    private int top;
    private int[] array;
    private int capacity;
    
    public Stack(int capacity) {
        this.capacity = capacity;
        array = new int[capacity];
        top = -1;
    }

    public void push(int data) {
        if (isFull()) {
            throw new StackOverflowError("Stack is full");
        }
        array[++top] = data;
    }

    public int pop() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        return array[top--];
    }

    public boolean isEmpty() {
        return top == -1;
    }

    public boolean isFull() {
        return top == capacity - 1;
    }

    public int peek() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        return array[top];
    }
}

Before we move on, let's dive into the details of this implementation.

  • The push() method is responsible for adding an element to the stack. It first checks if the stack is full, and if not, it adds the new element to the top of the stack.
  • The pop() method is responsible for removing an element from the stack. It first checks if the stack is empty, and if not, it removes and returns the top element from the stack.
  • The peek() method is responsible for returning the top element from the stack, without removing it.
  • The isEmpty() method is responsible for checking if the stack is empty.
  • The isFull() method is responsible for checking if the stack is full.

Advantages and Disadvantages of Using an Array in Stack Implementation

Advantages

  • Array-backed stacks are simple to implement and can be faster than linked list implementations, especially for small to medium sized stacks.
  • Arrays provide direct memory access which is faster than traversing through a linked list.
  • Array-backed stacks use less memory as the overhead of nodes is eliminated.

Disadvantages

  • The size of the array must be predetermined, which limits the size of the stack.
  • Resizing an array-backed stack is expensive as the entire stack must be copied to a larger array.
  • Memory allocated to an array-backed stack is fixed, which can result in wasted memory if the stack is not fully used.

Java Collections

In addition to implementing a stack using an array, Java provides a built-in Stack class that implements the stack data structure using a Vector. However, this implementation is considered obsolete and is not recommended for use in new projects. Instead, it is recommended to use the Deque interface from the Java Collections Framework.

A Deque is a double-ended queue, which can be used as a stack by adding and removing elements from the same end. Here is an example code snippet to get you started:

Deque<Integer> stack = new ArrayDeque<>();
stack.push(1);
stack.push(2);
stack.push(3);
System.out.println(stack.pop()); // Output: 3

Learn Java

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If you are new to Java and want to learn more about the language, we recommend checking out our other articles on Java programming. Here are a few to get you started:

  • Java vs Python: Which One is Better for Beginners?
  • Top 10 Programming Languages to Learn in 2023
  • What's New in Java 17?

FAQ

Can you implement a stack using an array?

Yes, a stack can be implemented using an array in Java. Array-backed stacks are simple to implement and can be faster than linked list implementations, especially for small to medium sized stacks.

What is implementation of a stack using an array?

Implementation of a stack using an array involves creating an array and adding elements to the top of the array using the push() method and removing elements from the top of the array using the pop() method.

Can we implement a stack using ArrayList in Java?

Yes, a stack can be implemented using ArrayList in Java. However, ArrayList uses dynamic arrays internally, which can be slower than array-backed stacks for small to medium sized stacks.

Quick Tips and Facts

  • The push() and pop() operations in array-backed stacks have a time complexity of O(1).
  • Resizing an array-backed stack can take O(n) time, where n is the number of elements in the stack.

Conclusion

In conclusion, implementing a stack in Java using an array is a simple and efficient way to handle Last In First Out data. Array-backed stacks are fast, efficient, and easy to implement, however, they have limitations in terms of predetermined size and resizing. Java also provides a built-in Stack class and the Deque interface from the Java Collections Framework as alternative implementations. We hope this article has helped you understand the basics of implementing a stack in Java using an array.

If you are looking to implement a stack in Java using an array, we recommend trying out the code snippet we provided and tweaking it as per your requirements. If you have any questions or comments, feel free to leave them below. At Stack Interface™, we are committed to providing expert advice and guidance to our readers.

Jacob
Jacob

Jacob is a software engineer with over 2 decades of experience in the field. His experience ranges from working in fortune 500 retailers, to software startups as diverse as the the medical or gaming industries. He has full stack experience and has even developed a number of successful mobile apps and games.

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