ArrayList Practice Questions

What method is used to get the number of elements in an ArrayList?

• length()

• count()

• size()

• numberOfElements()

Which of the following is NOT true about ArrayLists?

• They can hold primitive types directly

• They are mutable

• They are part of the java.util package

• They can change size during runtime

Why do ArrayLists use get and set methods instead of the index operator?

• Because ArrayLists are not built-in types.

• Because ArrayLists are a class with methods.

• Because ArrayLists do not support indexing.

• Because ArrayLists are immutable.

Which statement below is the correct way to retrieve the first element in the nums ArrayList?

• nums.get(0)

• nums[0]

• nums(0)

• nums[1]

What is the starting index of an ArrayList?

• 1

• 0

• -1

• 10

What happens automatically when primitive types are added to an ArrayList?

• They are converted to strings

• They are wrapped in objects

• They are ignored

• They are stored as is

What is the correct way to add an integer to an ArrayList in all Java versions?

• list.add(new Integer(5));

• list.add(5);

• list.add(Integer.valueOf(5));

• list.add(5.0);

What happens when you use the add(index, obj) method in an ArrayList?

• It removes the object at the index.

• It adds the object at the index and shifts others.

• It appends the object to the end.

• It clears the list.

Which method would you use to replace an element at a specific index in an ArrayList?

• set(int index, E obj)

• replace(int index, E obj)

• modify(int index, E obj)

• change(int index, E obj)

What will be printed?

List<Integer> list1 = new ArrayList<Integer>();

list1.add(5);

list1.add(4);

list1.add(3);

list1.add(1, 2);

System.out.println(list1);

• [5, 4, 3, 2]

• [5, 4, 1, 3]

• [2, 5, 4, 3]

• [5, 2, 4, 3]