Please answer the question in description

Question

Assume that the following numbers belonged to an ArrayList called values:

5, 23, 45, −3, 17, 18, 100

Which of the following would determine how many elements are in values?

a	int numElements = values.length;
b	int numElements = values.length();
c	int numElements = values.size();
d	int numElements = values.size;
e	double numElements = values.size;

Answer 1

As stated, values is an ArrayList, the correct way to determine how many elements it contains is by using the size() method. The statement int numElements = values.size(); creates an integer variable called numElements and stores the number of items currently inside the ArrayList. In this case, the list contains the numbers 5, 23, 45, -3, 17, 18, 100 so values.size() would return 7. The other choices are incorrect because .length is used for regular arrays, length() is used for strings, and .size() without parentheses is invalid since size() is a method that must be called with parentheses.

So, the final answer is C - int numElements = values.size().

Answer 2

Approaching this question in such a way to eliminate answers, you can start with the .length() method.

length() method of the String class in java and is used to measure the length of a string, not number of items in an array. This would eliminate option B.

Now that leaves size, size() and length(). There is no size variable so that eliminates D and E.

Leaving just .size() and .length(). This part could be confusing and unsure of if you mean Array or ArrayList i'll explain both.

If your variable is of type Array, the answer would be just B as there is no size method that applies to Arrays, just a length variable (so arrayElements.length).

If your variable is of type just ArrayList, the answer would be C, size() as ArrayList inherits the List interface and there is .length variable for ArrayList class.

TLDR:

If variable is truly of type ArrayList - option C is answer.

If variable is of type Array - option B is answer.