JAVA EE: How to use the Intermediate operations[forEach, collect and count] of Java 8 Stream

Monday, 23 October 2017

How to use the Intermediate operations[forEach, collect and count] of Java 8 Stream

Click here to watch in Youtube :
https://www.youtube.com/watch?v=CtDT0Gw0-Fc&list=UUhwKlOVR041tngjerWxVccw

StreamDemo1.java

import java.util.Arrays;
import java.util.List;

/**
 * Terminal operation : foreach()
 */
public class StreamDemo1
{
    public static void main(String[] args)
    {
        List<String> list = Arrays.asList("Ball", "Cat", "Dog", "Apple");

        /*
         * foreach operations helps iterate the elements of the Stream.
         */
        list.stream().sorted().filter((s) -> !s.startsWith("B"))
                .map(String::toUpperCase).forEach(System.out::println);
    }

}

Output

APPLE
CAT
DOG

StreamDemo2.java

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Terminal operation : collect()
 */
public class StreamDemo2
{
    public static void main(String[] args)
    {
        Stream<String> stream = Stream.of("Apple", "Ball", "Cat");

        /*
         * collect() operation helps to collect the stream result in a
         * collection like list.
         */
        List<String> list = stream.collect(Collectors.toList());
        System.out.println(list);
    }

}

Output

[Apple, Ball, Cat]

StreamDemo3.java

import java.util.Arrays;
import java.util.List;

/**
 * Terminal Operation : count()
 */
public class StreamDemo3
{
    public static void main(String[] args)
    {
        List<String> list = Arrays.asList("Ball", "Dog", "Apple");

        /*
         * count() operation return the aggregate count for stream data.
         */
        long count = list.stream().filter((s) -> s.startsWith("B")).count();

        System.out.println(count);
    }

}