The first step in implementing a data structure consists in defining the set of operations: Create a new file "StackADT. java" which contains the interface belown Interface StackADTeE) void push (Ex): E popil; E top (); bootean isEmpty (1): ? Stack based LinkedList implementation 1. Go to the List interface and add a method to get the value of the head You should also add the implementation of the method the the Linkedlist and DoublyLinkedL ist classes. public E gethead()f: if(l empty()) return head.data; return nutl; 2. The Stack class class StackeEs implements StackADTeE> \{ //ToDo Implementing the checkBalance method Given an expression string exp, write a program to examine whether the pairs and the orders of " 7,"7, " (",7) " "[", "]" are correct in exp. static bootean checkBalance(string expri f // Tobe 3