Defining the Abstract Data Type Stack The first step in implementing a data structure consists in defining the set of operations: Create a new file "StacknDT. java" which contains the interface betow: Interface StackADTeE>\{ void push (Ex) : E pop (); E top(): boolean isEnpty () : \} 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 DoublyLinkedList classes. public E getHead()\{ if(l empty()) return head.data; return null; 2. The Stack class class 5 tackeE> implenents: 5 tackADT f 1/ToD0 3 Implementing the checkBalance method Given an expression string exp, write a program to examine whether the pairs and the orders of " [*"},"(" " " ] static bootean checibalance(string expr) 1 //ToDo y Implementing the checkBalance method Given an expression string exp, write a progoam to examine whether the poirs and the orders of " 7,7;7;,7;, [,77 sce correct in exp. static bootean checkeylance(string expr] \& I/ ToDe )