Introduction to ArrayList

#Introduction to the Java Collections Framework

The Java Collections Framework is a set of different data structures used to store data. They consist of several types: sets, lists, deques, and maps. Each of these has subtypes, which are separate classes.

• Sets are data types where each item occurs only once, and the data is unordered.
• Lists are collections of items that can repeat, and the data is ordered.
• Deques are similar to lists but items can only be added or removed at the beginning and the end, not in the middle.
• Maps are pairs with a key and a value to represent pairs of items, such as a name and an address. The main type of data structure that we are concerned with is lists. There are two main types of lists: LinkedLists and ArrayLists, which differ in their method of accessing elements.

With LinkedLists, we can only access elements in order. If we want to access the 8th element, we have to start with the first element and then traverse through the LinkedList in order.

On the other hand, with ArrayLists, we can access elements in the middle of the list much more easily, using a single method call, covered in Topic 7.2. ## Generics

The Java Collections Framework, including ArrayLists, only accepts objects ...