What's the right Java generic for a collection of elements with unique addressable indices?

Question

I'm on my way to programming a database application and in our course we are told to implement a library of elements using one of the Java Collections. Each of the elements has a unique ID with which it's supposed to be addressed. Now I am wondering how this can be done.

I though about using a ListArray but this won't work because the only way of addressing List elements is through the index which you can't control.

Do you have some advice for me?

Answer 1

As the comments have said, you want to use a Map , of which HashMap is an implementation.

Map<String, String> library = new HashMap<String, String>();

library.put("key", "value");

String value = library.get("key");

Answer 2

Map<IndexType, YourEntityType> . Map is an interface; the most commonly used implementation is HashMap .