Java 8 Stream Intermediate operations examples | Streams in Java 8

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StreamDemo1.java

import java.util.ArrayList;
import java.util.List;

/**
 * 
 * Intermediate operations return the stream itself so you can chain
 * multiple method calls in a row.
 *
 */
public class StreamDemo1
{
    public static void main(String[] args)
    {
        List<String> nameList = new ArrayList<>();
        nameList.add("Amitabh");
        nameList.add("Shekhar");
        nameList.add("Aman");
        nameList.add("Rahul");
        nameList.add("Shahrukh");
        nameList.add("Salman");
        nameList.add("Yana");
        nameList.add("Lokesh");

        /*
         * Filter accepts a predicate to filter all elements of the
         * stream. This operation is intermediate which enables us to
         * call another stream operation (e.g. forEach) on the result.
         */
        nameList.stream().filter((s) -> s.startsWith("A"))
                            .forEach(System.out::println);
    }
}

Output

Amitabh
Aman

StreamDemo2.java

import java.util.ArrayList;
import java.util.List;

/**
 * 
 * Intermediate operations return the stream itself so you can chain
 * multiple method calls in a row.
 *
 */
public class StreamDemo2
{
    public static void main(String[] args)
    {
        List<String> nameList = new ArrayList<>();
        nameList.add("Amitabh");
        nameList.add("Shekhar");
        nameList.add("Aman");
        nameList.add("Rahul");
        nameList.add("Shahrukh");
        nameList.add("Salman");
        nameList.add("Yana");
        nameList.add("Lokesh");

        /*
         * The intermediate operation map converts each element into
         * another object via the given function. The following
         * example converts each string into an upper-cased string.
         * But you can also use map to transform each object into
         * another type.
         */
        nameList.stream().filter((s) -> s.startsWith("S"))
                         .map(String::toUpperCase)
                         .forEach(System.out::println);
    }
}

Output

SHEKHAR
SHAHRUKH
SALMAN

StreamDemo3.java

import java.util.ArrayList;
import java.util.List;

/**
 * 
 * Intermediate operations return the stream itself so you can chain
 * multiple method calls in a row.
 *
 */
public class StreamDemo3
{
    public static void main(String[] args)
    {
        List<String> nameList = new ArrayList<>();
        nameList.add("Amitabh");
        nameList.add("Shekhar");
        nameList.add("Aman");
        nameList.add("Rahul");
        nameList.add("Shahrukh");
        nameList.add("Salman");
        nameList.add("Yana");
        nameList.add("Lokesh");

        /*
         * Sorted is an intermediate operation which returns a sorted
         * view of the stream. The elements are sorted in natural
         * order unless you pass a custom Comparator.
         * 
         * Keep in mind that sorted does only create a sorted view of
         * the stream without manipulating the ordering of the backed
         * collection. The ordering of memberNames is untouched.
         */
        nameList.stream().sorted().map(String::toUpperCase)
                                  .forEach(System.out::println);
    }
}

Output

AMAN
AMITABH
LOKESH
RAHUL
SALMAN
SHAHRUKH
SHEKHAR
YANA

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/bc0205890e206d66c03b068b168e05c78f68f50d/BasicJava/StreamDemo_im_op_examples_App/?at=master

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