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Java Active Learning WorkBook: Scaffolded Programming Activities Beyond The Basics.

Celine Latulipe, Devon Blewett, Lara De Leon

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Section 7.1 Check Your Understanding

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Exercises Exercises

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1. ArrayList: Elements.

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    An ArrayList can store objects and primitives such as int, double, boolean.

  • True.

  • ArrayLists cannot store the following: int, double, boolean, char, float, long, byte, short. A workaround is to use Wrapper classes.

  • False.

  • ArrayLists cannot store the following: int, double, boolean, char, float, long, byte, short. A workaround is to use Wrapper classes.
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2. ArrayList: Accessing Elements.

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    How would we access the first element in the ArrayList list?
  • list.item(0)
  • Incorrect: ArrayList does not have a .item() method.
  • list.get(0)
  • Correct: In ArrayLists, we use the .get(i) method to access the element at index i.
  • list[0]
  • Incorrect: Square brackets are used for accessing elements in an array, not an ArrayList.
  • list.set(0, element)
  • Incorrect: The .set(index, element) method is used to replace the element at the specified index with the specified element. It is not used for accessing elements.
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3. ArrayList: Features.

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    Which of the following are true about an ArrayList? (Select all that apply)
  • ArrayLists have a dynamic size.
  • Correct: Unlike partially-filled arrays, ArrayLists automatically resize themselves when an element is added or removed.
  • ArrayLists have a fixed size.
  • Incorrect: ArrayLists resize automatically when an element is added or removed while partially-filled arrays require manual resizing if you have reached capacity and are trying to add an element.
  • ArrayLists use the .length() method to get the number of elements in the list.
  • Incorrect: ArrayLists use .size() while arrays use .length().
  • ArrayLists cannot be instantiated without importing from the Java Library.
  • Correct: To use ArrayLists, you must import the java.util.ArrayList package first.
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