For others cases, immutable collections are better. union: Returns all elements of two collections.įor some cases, it is better to use mutable collections.tail: return all element except the first one.take: return the first n element from collection.product: return the multiplication of the element in the collection.max: return the maximum element in the collection.'two') Makes the mutable collections easy to access Creates an empty. last: return last element in the collection Table 17.2 continued import val words mutable.isEmpty: return true if the collection is empty.head: return first element in the collection.groupBy: group collection elements into a Map of Collections.Foreach: apply function to all element in the collection.Find: return first element that makes the predict return true.Filter: take predict and return all elements that make the predict true.Diff: return the difference between two collection.Collect: return a new collection by applying a function to each element of the old collection.Most of the methods take either a function or predict (a function that take one or more parameters and return Boolean). Scala Collections provide us with a lot of methods that can manipulate data. The below table lists the Immutable/Mutable Sequences (Linear or Indexed) with descriptions: Indexed allows you to access the item directly by their index (random accessed).

In general, immutable sequence list will not allow you to modify its items once it has been added. In order to choose the suitable sequence, you have to think about two important aspects:

Set: it is a unique collection of elements (no duplication).Ĭhoosing the Suitable Sequence Collection.

Map: it is a collection of key/value pairs. Scalas collections make it easy for you to manipulate arrays, linked lists, sets, maps and other data structures in convenient ways, providing built-in many of.Sequence: it is a collection of indexed or linear elements (linear means like a linked list, but indexed means I can access any element directly using its index).Then, as shown in (Figure 1), it is divided into three categories: Choosing the suitable Sequence CollectionĬollection Classes start from Traversable trait (it is something near to Java Interface).Scala Collection Classes exist in Package “llection” or one of its sub-packages.Īnd, I would like to discuss the following points about Scala Collections:

Scala collections