collections_framework_demo.java

import java.util.*;

public class DataStructureDemo {

    public static void main(String[] args) {

        System.out.println("=== STACK Example ===");
        Stack<Integer> stack = new Stack<>();
        stack.push(10);
        stack.push(20);
        stack.push(30);
        System.out.println("Stack: " + stack);

        System.out.println("Popped element: " + stack.pop());
        System.out.println("Top element: " + stack.peek());
        System.out.println("Stack after pop: " + stack);
        System.out.println();

        System.out.println("=== QUEUE Example ===");
        Queue<String> queue = new LinkedList<>();
        queue.add("A");
        queue.add("B");
        queue.add("C");
        System.out.println("Queue: " + queue);

        System.out.println("Removed element: " + queue.remove());
        System.out.println("Front element: " + queue.peek());
        System.out.println("Queue after removal: " + queue);
        System.out.println();

        System.out.println("=== LINKED LIST Example ===");
        LinkedList<String> list = new LinkedList<>();
        list.add("Node1");
        list.add("Node2");
        list.addFirst("Start");
        list.addLast("End");
        System.out.println("LinkedList: " + list);

        list.remove("Node2");
        System.out.println("After removing Node2: " + list);
        System.out.println();

        System.out.println("=== TREE Example (TreeSet) ===");
        TreeSet<Integer> tree = new TreeSet<>();
        tree.add(50);
        tree.add(20);
        tree.add(70);
        tree.add(10);
        System.out.println("TreeSet (sorted): " + tree);

        System.out.println("First element: " + tree.first());
        System.out.println("Last element: " + tree.last());
        System.out.println("Tree higher than 20: " + tree.higher(20));
        System.out.println();

        System.out.println("=== END OF PROGRAM ===");
    }
}