What is an iterator Scala?

An iterator is a way to access elements of a collection one-by-one. It resembles to a collection in terms of syntax but works differently in terms of functionality. An iterator defined for any collection does not load the entire collection into the memory but loads elements one after the other.

Is iterator a method or class in Scala?

An iterator is not a collection, but rather a way to access the elements of a collection one by one. The two basic operations on an iterator it are next and hasNext.

What is an iterator example?

An Iterator is an object that can be used to loop through collections, like ArrayList and HashSet. It is called an “iterator” because “iterating” is the technical term for looping. To use an Iterator, you must import it from the java. util package.

How do you write a loop in Scala?

In Scala, for-loop allows you to filter some elements from the given collection using one or more if statements in for-loop. Syntax: for(i<- List if condition1; if condition2; if condition3; …) { // code.. }

Are Scala iterators lazy?

Unlike operations directly on a concrete collection like List , operations on Iterator are lazy.

What is Scala list?

A list is a collection which contains immutable data. List represents linked list in Scala. The Scala List class holds a sequenced, linear list of items. Lists are immutable whereas arrays are mutable in Scala. Lists represents a linked list whereas arrays are flat.

What is zip in Scala?

Advertisements. zip() method is a member of IterableLike trait, it is used to merge a collection to current collection and result is a collection of pair of tuple elements from both collections.

How do you break a while loop in Scala?

import scala. util. control. _ object demo_brk_963 { def main(args: Array[String]) { var a = 0; var b = 0; val numList1 = List(1,2,3,4,5,6,7,8,9,10); val numList2 = List(11,12,13); val outer = new Breaks; //object for break val inner = new Breaks; //object for break outer.

Is Scala lazy by default?

In Scala (like most other languages) they are. This strategy carries over to other contexts, including vals and vars. It would be awkward to break this rule for vals, but laziness can be useful and provided as an opt-in. As you noted, dependency on mutable variables is incompatible incompatible with lazy evaluations.

Is Scala map lazy?

Scala collections are by default strict in all their transformers, except for Stream , which implements all its transformer methods lazily. However, there is a systematic way to turn every collection into a lazy one and vice versa, which is based on collection views.

What are the methods of an iterator in Scala?

Two important methods in Scala Iterator are next () and hasNext. hasNext will tell if there is another element to return, while next () will return that element. 3. Declaring a Scala Iterator Basically, to declare an iterator in Scala over a collection, we pass values to Iterator (). 4. Accessing values with a Scala Iterator

How is an iterator used in a collection?

An iterator is not a collection, but rather a way to access the elements of a collection one by one. The two basic operations on an iterator it are next and hasNext. A call to it.next () will return the next element of the iterator and advance the state of the iterator.

Which is an example of a traversable in Scala?

A common use case of TraversableOnce is as an argument type for methods that can take either an iterator or a traversable as argument. An example is the appending method ++ in class Traversable. It takes a TraversableOnce parameter, so you can append elements coming from either an iterator or a traversable collection.

What happens If hasNext is false in Scala?

If hasNext returns false, then the iterator is empty. If we can repeatedly traverse the iterator, this returns true; otherwise, false. Here, this returns the number of elements in the iterator. Once we’ve called this method, the iterator exhausts. This applies the function to every value in the iterator and then returns a new iterator from this.