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

What must be defined if you want to make your own type of Map?

1. An implementation of the Map.Entry interface

2. A unique key generation method

3. A custom hashing function

4. A sorting algorithm

The correct answer is: An implementation of the Map.Entry interface

When creating your own type of Map, you must define an implementation of the Map.Entry interface. This is because the Map interface itself does not contain all of the methods required to implement a Map. Without defining this implementation, your custom Map will not work correctly. The other options listed, while related to Maps, do not cover all of the necessary components for creating a new type of Map. A unique key generation method is important for ensuring that each key in the Map is unique, but it does not cover all aspects of a Map. A custom hashing function is also useful for efficient storage and retrieval of data, but it is not the only requirement for creating a new type of Map. A sorting algorithm is used for ordering elements in a collection, but is not a necessary component for creating a Map.