Consider the code snippet shown below:

Stack<String> words1 = new Stack<>();

Stack<String> words2 = new Stack<>();

words1.push("abc");

words1.push("def");

words1.push("ghi");

while (!words1.empty())

{

   words2.push(words1.pop());

}

while (!words2.empty())

{

   System.out.print(words2.pop());

}

What will be printed when this code is executed?

Assume that you have declared a stack named myStack to hold String elements. Which of the following statements will correctly retrieve the top element from myStack without removing it? 

Assume that you have declared a stack named myStack to hold String elements. Which of the following statements will correctly remove an element from myStack? 

Assume that you have declared a stack named myStack to hold String elements. Which of the following statements will correctly add an element to myStack? 

Which of the following correctly declares a stack that will hold String elements? 

An Undo feature in a word processor program that allows you to reverse a previously completed command is probably implemented using which structure type?

Which of the following statements about stacks is correct?

You intend to use a hash set with your own object class. Which of the following statements is correct? 

You need to write a program to simulate the effect of adding an additional cashier in a supermarket to reduce the length of time customers must wait to check out.  Which data structure would be most appropriate to simulate the waiting customers?

What operation is least efficient in a LinkedList?