Wednesday 6 September 2017

How to use flatMap method of Java 8 streams | Streams in Java 8


Click here to watch in Youtube :
https://www.youtube.com/watch?v=b75LVKzjiEc&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge
How to use flatMap method of Java 8 streams | Streams in Java 8
How to use flatMap method of Java 8 streams | Streams in Java 8
FlatMapDemo.java
import java.util.Arrays;
import java.util.stream.Stream;

public class FlatMapDemo
{
    public static void main(String[] args)
    {

        String[][] strArray = new String[][] { { "a", "b" }, { "c", "d" }, { "e", "f" } };

        // Stream<String[]>
        Stream<String[]> strArrayStream = Arrays.stream(strArray);
        
        //Convert  Stream<String[]> to Stream<String>
        Stream<String> strStream = strArrayStream.flatMap((x -> Arrays.stream(x)));

        // filter a stream of string
        Stream<String> filterdStream = strStream
                .filter(x -> "c".equals(x.toString()));

        filterdStream.forEach(System.out::println); //Output is c
    }

}
Output
c

NonFlatMapDemo.java
import java.util.Arrays;
import java.util.stream.Stream;

/**
 * 
 * This example will print an empty result, because filter() has
 * no idea how to filter a stream of String[].
 *
 */
public class NonFlatMapDemo
{
    public static void main(String[] args)
    {

        String[][] strArray = new String[][] { { "a", "b" }, { "c", "d" },{ "e", "f" } };

        // Stream<String[]>
        Stream<String[]> strArrayStream = Arrays.stream(strArray);

        // filter a stream of string[], and return a string[]?
        Stream<String[]> filterdStream = strArrayStream
                .filter(x -> "c".equals(x.toString()));

        filterdStream.forEach(System.out::println); //Output is empty...
    }

}
Output
//Output is empty...

Click the below link to download the code:
https://sites.google.com/site/ramj2eev1/home/javabasics/StreamDemo_flatMap.zip?attredirects=0&d=1

Github Link:
https://github.com/ramram43210/Java/tree/master/BasicJava/StreamDemo_flatMap

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/53e39342c1c41555c6e548783b3cf96ab7bd9ee6/BasicJava/StreamDemo_flatMap/?at=master

See also:

  • All JavaEE Viedos Playlist
  • All JavaEE Viedos
  • All JAVA EE Links
  • Servlets Tutorial
  • All Design Patterns Links
  • JDBC Tutorial
  • Java Collection Framework Tutorial
  • JAVA Tutorial
  • Kids Tutorial
  • No comments:

    Post a Comment