1.1: Why are there two kinds of List?

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When people start working with the Java Collections Framework, they are sometimes confused about ArrayList and LinkedList. Why does Java provide two implementations of the List interface? And how should you choose which one to use? We will answer these questions in the next few chapters.

I’ll start by reviewing interfaces and the classes that implement them, and I’ll present the idea of “programming to an interface”.

In the first few exercises, you’ll implement classes similar to ArrayList and LinkedList, so you’ll know how they work, and we’ll see that each of them has pros and cons. Some operations are faster or use less space with ArrayList; others are faster or smaller with LinkedList. Which one is better for a particular application depends on which operations it performs most often.