Mapping Operations in Stream

Mapping operations are those operations that transform the elements of a stream and return a new stream with transformed elements.

We can use a variety of methods to transform a stream into another stream object. The two most common methods used are map() and flatMap().

Understanding map()

The map() method takes a lambda expression as its only argument and uses it to change every individual element in the stream. Its return value is a new stream object containing the changed elements.

Below is the method definition:

<R> Stream<R> map(Function<? super T, ? extends R> mapper)

Input Parameter -> A function to apply to each element.

Return Type -> Returns a stream consisting of the results of applying the given function to the elements of the stream.

Let’s look at a basic example of map(). In the below example, we have a list of names. We need to print all the names on the list in the upper case.