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

What effect does a good hash function have?

1. It guarantees no collisions

2. It speeds up data retrieval

3. It decreases memory usage

4. It simplifies the code

The correct answer is: It speeds up data retrieval

A good hash function speeds up data retrieval by ensuring that data items are assigned to unique locations in a hash table, thereby eliminating the need for linear search. Option A is incorrect because even with a good hash function, collisions can still occur. Option C is incorrect because a good hash function does not necessarily decrease memory usage, as the hash table still needs to store the same amount of data. Option D is incorrect because a good hash function does not necessarily simplify the code, as it may still require complex algorithms and logic.