IN JAVA

import java.util.*; public class OurStackExample2 { public static void main (String[] argv) { String s = "((()))"; checkParens (s); s = "()(())()"; checkParens (s); s = "((())"; checkParens (s); } static void checkParens (String inputStr) { // Extract the letters from the String into a char array. char[] letters = inputStr.toCharArray(); // Create an instance of the stack. OurStack2 stack = new OurStack2 (); boolean unbalanced = false; for (int i=0; i 
 
 
import java.util.*; public class OurStack2 { ArrayList array; int top; public OurStack2 () { // Can be unlimited in size now. array = new ArrayList(); top = 0; } public void push (char ch) { // INSERT YOUR CODE } public char pop () { // INSERT YOUR CODE } public boolean isEmpty () { // INSERT YOUR CODE } }
 
 
 
  In-Class Exercise 7: Download OurStackExample2.java and modify OurStack2.java to use an ArrayList instead of an array. This way, there's no upper limit to the size. What part of the code changes from the original ourStack.java? Do we still need to check for a lower limit in pop()