one_Execution.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 15-Feb-21
 *   Time: 10:35 AM
 *   File: Execution.java
 */

package feb15_21_NK.one;

public class Execution {
    public static void main(String[] args) {
        StackUsingLinkedList stack = new StackUsingLinkedList();
        System.out.println(stack.isEmpty());
        stack.push(new Node(5));
        System.out.println(stack.isEmpty());
        stack.peek();
        stack.push(new Node(6));
        stack.peek();
        //stack.pop();
        stack.peek();
        stack.print();
    }
}

one_Node.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 15-Feb-21
 *   Time: 10:17 AM
 *   File: Node.java
 */

package feb15_21_NK.one;

public class Node {
    public int data;
    public Node next; // self reference structure

    public Node() {
        data = 0;
        next = null;
    }

    public Node(int d) {
        data = d;
        next = null;
    }
}

one_StackUsingLinkedList.java

/*   Created by IntelliJ IDEA.
 *   Author: Kshitij Varshney (kshitijvarshne1)
 *   Date: 15-Feb-21
 *   Time: 10:20 AM
 *   File: StackUsingLinkedList.java
 */

package feb15_21_NK.one;

public class StackUsingLinkedList {
    Node top;

    public StackUsingLinkedList() {
        top = null;
    }

    public boolean isEmpty() {
        return top == null;
    }

    public boolean isFull() {
        return false;
    }

    public void push(Node newNode) {
        if (top == null) {
            top = newNode;
            return;
        }
        newNode.next = top;
        top = newNode;
    }

    public void peek() {
        if (isEmpty()) {
            System.out.println("stack is empty");
            return;
        }
        System.out.println(top.data);
    }

    public void print() {
        if (isEmpty()) {
            System.out.println("stack is empty");
            return;
        }
        Node temp = top;
        while (temp != null) {
            System.out.print(temp.data+" -> " );
            temp = temp.next;
        }
    }

    public void pop() {
        if (isEmpty()) {
            System.out.println("stack is empty");
            return;
        }
        top = top.next;
    }
}