Tuesday, 25 July 2017

How to use map method of stream to convert all string elements in an array to uppercase


Click here to watch in Youtube : 
https://www.youtube.com/watch?v=jl61UnWSkQQ&list=UUhwKlOVR041tngjerWxVccw

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

/**
 * Once you have a Stream object, you can use a variety of methods to
 * transform it into another Stream object. The first such method
 * we’re going to look at is the map method. It takes a lambda
 * expression as its only argument, and uses it to change every
 * individual element in the stream. Its return value is a new Stream
 * object containing the changed elements.
 *
 * How to use map to convert all elements in an array of strings to
 * uppercase.
 */
public class StreamDemo
{
    public static void main(String[] args)
    {
        String[] nameArray = new String[] { "Peter", "Steve", "paul", "Ram" };

        Stream<String> stream = Arrays.stream(nameArray);

        /*
         * passing a lambda expression, one which can convert a string
         * to uppercase.
         *
         * The Stream object returned contains the changed strings.
         */
        Stream<String> upperCaseStream = stream.map(name -> name.toUpperCase());

        String[] upperCaseNameArray = upperCaseStream.toArray(String[]::new);

        for (String name : upperCaseNameArray)
        {
            System.out.println(name);
        }

    }
}
Output
PETER
STEVE
PAUL
RAM

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/0b972e391c9826af8cfcb6980bab82db213fedd5/BasicJava/StreamDemo_map_uppercase_App/?at=master

See also:
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