Java Program to demonstrate stack class in Collection framework

Program

package stackPack;
import java.util.*;
public class StackCollectionDemo
{
	public static void main(String[] args)
	{
		Stack st = new Stack();
		System.out.println("Contents of stack:\t" + st);
		System.out.println("Is stack empty?:\t" + st.empty());
		st.push(15);
		st.push(25);
		st.push(35);
		st.push(45);
		System.out.println("Contents of stack:\t" + st);
		System.out.println("Index of searched element (15):\t" + st.search(15));
		System.out.println("Top of the stack is:\t" + st.peek());
		st.pop();
		st.pop();
		System.out.println("Contents after pop operation:\t" + st);
	}
}

This Java program demonstrates the use of the Stack class from the Java Collection Framework.

1. Stack Class:

   • The Stack class in Java provides a last-in-first-out (LIFO) data structure.
   • It is a part of the java.util package and extends Vector.

2. Program Workflow:

   • Initialization: Creates an empty Stack object named st.
   • Checking Empty Stack: Uses the empty() method to check if the stack is empty.
   • Push Operation:
     • Adds elements (15, 25, 35, 45) to the stack using the push() method.
   • Display Contents: Prints the contents of the stack after push operations.
   • Search Operation: Uses the search() method to find the position of an element (15) in the stack.
   • Peek Operation: Uses the peek() method to display the top element of the stack without removing it.
   • Pop Operation:
     • Removes the top elements of the stack using the pop() method.
     • Prints the updated stack contents after popping elements.

3. Output Messages:

   • Provides information about the stack contents, whether it's empty, the top element, and the result of the search.

4. Key Methods of Stack Used:

   • push(E element): Adds an element to the top of the stack.
   • pop(): Removes and returns the top element of the stack.
   • peek(): Returns the top element without removing it.
   • empty(): Checks if the stack is empty.
   • search(Object o): Returns the 1-based position of the element from the top of the stack. If not found, it returns -1.

Output

$ javac -d . StackCollectionDemo.java 
$ java stackPack.StackCollectionDemo 
Contents of stack:	[]
Is stack empty?:	true
Contents of stack:	[15, 25, 35, 45]
Index of searched element (15):	4
Top of the stack is:	45
Contents after pop operation:	[15, 25]