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

What advantage do wildcards provide over raw types in generics?

1. They allow for mixed types in the same collection

2. They provide type safety without knowing the exact generic type

3. They remove the need for casting objects

4. They make generic methods and classes simpler to write

The correct answer is: They provide type safety without knowing the exact generic type

Wildcards provide type safety without knowing the exact generic type, which is an advantage over raw types because it ensures that the collection contains only elements of a certain type, but still allows for flexibility in the specific type. A is incorrect because wildcards do not allow for mixed types in a single collection; they still ensure type safety. C is incorrect because casting is not necessary with generics, whether using wildcards or raw types. D is incorrect because while wildcards make generic methods and classes simpler to write, raw types provide no type safety at all and are generally considered bad practice.