Tuesday, 4 July 2017

How to filter the List of Names using Java 8 Stream | Java 8 streams tutorial | Streams in Java 8


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How to filter the List of Names using Java 8 Stream | Java 8 streams tutorial | Streams in Java 8 
FilterDemo.java
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class FilterDemo
{
    public static void main(String[] args)
    {
        List<String> namesList = Arrays.asList("Ram", "Peter","Pradeep", "Steve");

        List<String> filteredNameList = getFilterOutput(namesList, "P");
        for (String name : filteredNameList)
        {
            System.out.println(name); 
        }
    }

    private static List<String> getFilterOutput(List<String> namesList, String filter)
    {
        List<String> filteredNameList = new ArrayList<>();
        for (String name : namesList)
        {
            if (name.startsWith("P"))
            {
                filteredNameList.add(name);
            }
        }
        return filteredNameList;
    }
}
Output
Peter
Pradeep
StreamDemo1.java
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class StreamDemo1
{
    public static void main(String[] args)
    {
        List<String> namesList = Arrays.asList("Ram", "Peter","Pradeep", "Steve");

        /*
         * Convert list to stream.
         * 
         * Returns a sequential Stream with this collection as its
         * source.
         */
        Stream<String> stream = namesList.stream();
        /*
         * filters the name, starts with "P".
         * 
         * Returns a stream consisting of the elements of this stream
         * that match the given predicate.
         */
        stream = stream.filter(name -> name.startsWith("P"));

        /*
         * Collect the output and convert streams to a List.
         * 
         * Performs a mutable reduction operation on the elements of
         * this stream using a Collector.
         */
        List<String> filteredNameList = stream.collect(Collectors.toList());

        filteredNameList.forEach(System.out::println);
    }

}
Output
Peter
Pradeep
StreamDemo2.java
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class StreamDemo2
{
    public static void main(String[] args)
    {
        List<String> namesList = Arrays.asList("Ram", "Peter","Pradeep", "Steve");

        
        List<String> filteredNameList = namesList.stream() //convert list to stream
                .filter(name -> name.startsWith("P")) //filters the name, starts with "P".
                .collect(Collectors.toList()); //collect the output and convert streams to a List
        

        filteredNameList.forEach(System.out::println);
    }

}
Output
Peter
Pradeep
Refer:
https://docs.oracle.com/javase/8/docs/api/index.html?java/util/Collection.html

https://docs.oracle.com/javase/8/docs/api/index.html?java/util/stream/Stream.html

https://docs.oracle.com/javase/8/docs/api/index.html?java/util/function/Predicate.html

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/c8efc47167637d9bcc657c3cee2ad048e22a2b17/BasicJava/StreamDemo_nameList_filter_App/?at=master

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