Question

Consider a linked implementation of a Stack. Implement the pop() method below. Assume a typical singly linked node, with an instance variables data and next.

public class LinkedStack<T> implements Stack<T> {
private Node<T> head;
  
public LinkedStack() {
head = new Node<T>();
}

// pops the top item off the stack
// returning the popped value
// throw an EmptyStackException if there are no
// items in the stack
public T pop() {
// write your implementation below

}

}

Answer 1

SOLUTION :- pop() method for LinkedStack

import java.util.NoSuchElementException;

public class LinkedStack<T> implements Stack<T> {

// field (s ) of the LinkedStack class

private Node top;

// private class of Node data

private class Node {

// field (s ) of the Node class

T elt;

Node next;

// constructor of the Node class

Node(T elt, Node next) {

this.elt = elt;

this.next = next;

}

}

// returns true if the Stack is empty

public boolean isEmpty() {

return (top == null);

}

// pops the top element off the stack

// throws a NoSuchElementException if the stack is empty

public T pop() {

if (this.isEmpty())

throw new NoSuchElementException();

Node t = top;

top = t.next;

return t.elt;

}

}