Stack in Java

In Java, Stack is a class that implements a last-in, first-out (LIFO) data structure, which means that the last element added to the stack will be the first one to be removed. The Stack class provides a set of methods to add, remove, and access elements in the stack. In this answer, I will explain how to create and use a Stack in Java, as well as some of its commonly used methods.

Creating a Stack

To use Stack in Java, you must first import the java.util.Stack class. You can create a Stack in Java using the following code:

Stack<String> stack = new Stack<>();

In the above example, we create a new Stack that can hold elements of type String.

Adding and Removing Elements

Once a Stack has been created, elements can be added or removed from it using the following methods:

// Add an element to the top of the Stack
stack.push("apple");

// Remove and return the top element of the Stack
String top = stack.pop();

// Return the top element of the Stack without removing it
top = stack.peek();

// Remove all elements from the Stack
stack.clear();

Accessing Elements

Stack provides several methods to access elements in the stack:

// Get the index of the first occurrence of an element
int index = stack.search("banana");

// Get the size of the Stack
int size = stack.size();

Other Commonly Used Methods

Some other commonly used methods provided by the Stack class include:

// Check if the Stack is empty
boolean isEmpty = stack.empty();

// Convert the Stack to an array
String[] array = stack.toArray(new String[0]);

// Iterate over the elements in the Stack using a for-each loop
for (String element : stack) {
    System.out.println(element);
}

One thing to keep in mind when using Stack is that it is a legacy class, which means that it is not recommended to use it in new code. Instead, it is recommended to use the Deque interface, which provides a similar set of methods and is more flexible.