Review the following class definition in Java answer the following questions. class StackClass { private int [] stackRef; private int maxLen, topIndex; public StackClass() { // A constructor stackRef = new int [100]; maxLen = 99; topIndex = -1; } public void push(int number) { if (topIndex == maxLen) System.out.println("Error in pushstack is full"); else stackRef[++topIndex] = number; } public void pop() { if (empty()) System.out.println("Error in popstack is empty"); else --topIndex; } public int top() { if (empty()) { System.out.println("Error in topstack is empty"); return 9999; } else return (stackRef[topIndex]); } public boolean empty() {return (topIndex == -1);} } Create a main to run this class. a. Create a new StackClass variable. b. Push 2 numbers. c. Print out the top d. Pop a value e. Then print out the top again.