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

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Dive into the depths of Java with our quiz based on "Thinking in Java, Fourth Edition" by Bruce Eckel. Test your knowledge, solidify concepts, and prepare for certification with challenging questions and insightful feedback.

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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How can you get enum instances if 'values()' is not available due to upcasting?

Using 'getEnumConstants()' method
With reflection
Cannot get instances
Using 'valueOf()' method

The correct answer is: Using 'getEnumConstants()' method

After upcasting, the enum class is seen as a normal class, therefore the 'values()' method is no longer available. An alternative method to get the enum instances is by using the 'getEnumConstants()' method, which will return an array of all the enum instances. Option B, using reflection, is incorrect because it is not efficient and can only obtain the enum values one by one. Option C is also incorrect because, as mentioned before, the 'getEnumConstants()' method can return the enum instances. Option D, using 'valueOf()' method, is incorrect because this method only takes in a string parameter and returns an enum constant, not all the enum instances. Therefore, the correct answer is A.