Create StackOfLinkedList.java

data_structures/Stacks/StackOfLinkedList.java

@@ -0,0 +1,98 @@
+/**
+ *
+ * @author Varun Upadhyay (https://github.com/varunu28)
+ *
+ */
+
+// An implementation of a Stack using a Linked List
+
+class StackOfLinkedList {
+
+    public static void main(String[] args) {
+
+        LinkedListStack stack = new LinkedListStack();
+        stack.push(1);
+        stack.push(2);
+        stack.push(3);
+        stack.push(4);
+
+        stack.printStack();
+
+        System.out.println("Size of stack currently is: " + stack.getSize());
+
+        stack.pop();
+        stack.pop();
+
+    }
+
+}
+
+// A node class
+
+class Node {
+    public int data;
+    public Node next;
+
+    public Node(int data) {
+        this.data = data;
+        this.next = null;
+    }
+}
+
+/**
+ * A class which implements a stack using a linked list
+ *
+ * Contains all the stack methods : push, pop, printStack, isEmpty
+ **/
+
+class LinkedListStack {
+
+    Node head = null;
+    int size = 0;
+
+    public void push(int x) {
+        Node n = new Node(x);
+        if (getSize() == 0) {
+            head = n;
+        }
+        else {
+            Node temp = head;
+            n.next = temp;
+            head = n;
+        }
+        size++;
+    }
+
+    public void pop() {
+        if (getSize() == 0) {
+            System.out.println("Empty stack. Nothing to pop");
+        }
+
+        Node temp = head;
+        head = head.next;
+        size--;
+
+        System.out.println("Popped element is: " + temp.data);
+    }
+
+    public void printStack() {
+
+        Node temp = head;
+        System.out.println("Stack is printed as below: ");
+        while (temp != null) {
+            System.out.print(temp.data + " ");
+            temp = temp.next;
+        }
+        System.out.println();
+
+    }
+
+    public boolean isEmpty() {
+        return getSize() == 0;
+    }
+
+    public int getSize() {
+        return size;
+    }
+    
+}