codehub27: How to create a java program to Filtering and mapping a list of integers using Streams.

Streams are extremely useful in java 8 programming. A Basic introduction about streams in written in separate blog post. The link is given below.

Stream operations:

Stream operations are of two categories. One is intermediate operations. Another one is terminal operations.

Intermediate operations:

These are operations based on filtering, mapping and sorting data. Some of the functions are listed below.

filter() : Based on a condition, the data is filtered.

map() : Each and every element is transformed using this function.

flatmap() : It is used for nesting purpose.

distinct() : It gives you the unique value.

sorted() : It sorts the elements.

Terminal operations:

As a name indicated, this is the last operations in stream. It may be the end operation or produce the list.

for each() : This is a statement deals with iterative operations.

collect() : It collects thedata

count() : It returns the number of elements.

anymatch() : Checks the element and finds the match.

reduce() : Combines the element and produce the result.

Java program to Filtering and mapping a list of integers using Streams:

· As a beginning, create a class “StreamEg”. Save this file as “StreamEg.java”.

· Next, create a list of numbers using array.

· Filter the odd numbers separately.

· Create the square of the number by doubling them.

· Print the output list.

#Java Program

import java.util.Arrays;

import java.util.List;

import java.util.stream.Collectors;

//Create a class “StreamEg”

public class StreamEg {

public static void main(String[] args) {

//Create a list of integers and assign the values

List<Integer> nos = Arrays.asList(11, 12, 13, 14, 15, 16, 17, 18, 19, 20);

// Filtering odd numbers and square them using stream

List<Integer> oddSquare = nos.stream()

.filter(n -> n % 2 != 0)

.map(n -> n * n)

.collect(Collectors.toList());

//Print the value of list

System.out.println(oddSquare);

}

Once you run the program, you will get the output.

These are the ways of using Streams in java. Enjoy Coding!!!!

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