A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. In other words, the last element added to the stack will be the first one to be removed.
In Java, the java.util.Stack class is available to implement the stack data structure. It extends the Vector class and provides all the stack operations such as push, pop, peek, search, etc.
Creating a Stack in Java
To create a stack in Java, you can simply create an instance of the java.util.Stack class as follows:
Stack<Integer> stack = new Stack<>();
Here, we have created a stack of integers using the generic Stack class. You can replace Integer with any other object type.
Stack Operations
The following are the main stack operations that can be performed using the java.util.Stack class:
Push
The push operation adds an element to the top of the stack. It can be done using the push method as follows:
stack.push(10);
Pop
The pop operation removes and returns the top element of the stack. It can be done using the pop method as follows:
int topElement = stack.pop();
Peek
The peek operation returns the top element of the stack without removing it. It can be done using the peek method as follows:
int topElement = stack.peek();
Search
The search operation searches for an element in the stack and returns its position. The position is calculated as the distance from the top of the stack. If the element is not present in the stack, it returns -1. It can be done using the search method as follows:
int position = stack.search(10);
In conclusion, a stack is a useful data structure that can be easily implemented in Java using the java.util.Stack class. It provides all the necessary stack operations such as push, pop, peek, and search.