Mastering Java: The Ultimate Quiz for 'Thinking in Java'

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Prepare for your Java exam with our ultimate quiz based on 'Thinking in Java'. Engage with expertly crafted questions that enhance your learning process. Perfect for Java enthusiasts looking to solidify their knowledge!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

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Why does List<? extends Fruit> not accept new Apple() when calling add()?

Because the list is bound to Fruit objects only
Because the compiler cannot determine what specific subtype of Fruit should be accepted
Because Apple is not a subtype of Fruit
Because you can only add null to such a List

The correct answer is: Because the compiler cannot determine what specific subtype of Fruit should be accepted

List<? extends Fruit> means that the elements in the list can be any subtype of Fruit. When calling add(), the compiler cannot determine which specific subtype is expected in the list, so it will not allow adding a new Apple object. Option A is incorrect because the list is not limited to only Fruit objects, but rather any subtype of Fruit. Option C is incorrect because Apple is a subtype of Fruit. Option D is incorrect because any non-null object can be added to the list, not just null.