Monday, 29 May 2017

Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of Map]


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Java Tutorial: Lambda expression in java | Java Lambda expressions[forEach method of Map] 
LambdaDemo1.java
import java.util.LinkedHashMap;
import java.util.Map;

public class LambdaDemo1
{

    public static void main(String[] args)
    {

        Map<Integer, String> map = new LinkedHashMap<>();
        map.put(1, "Peter");
        map.put(2, "John");
        map.put(3, "Juli");
        map.put(4, "Stephan");

        /*
         * Normal way to loop a Map.Before Java 8
         */
        for (Map.Entry<Integer, String> entry : map.entrySet())
        {
            System.out.println("key : " + entry.getKey() + ", value : "
                                                           + entry.getValue());
        }

        System.out.println("------------------------------------");

        /*
         * In Java 8, we can loop a Map with forEach + lambda expression.
         */
        map.forEach((k, v) -> System.out.println("key : " + k + " value : " + v));

    }

}
Output
key : 1, value : Peter
key : 2, value : John
key : 3, value : Juli
key : 4, value : Stephan
------------------------------------
key : 1 value : Peter
key : 2 value : John
key : 3 value : Juli
key : 4 value : Stephan
LambdaDemo2.java
import java.util.LinkedHashMap;
import java.util.Map;

public class LambdaDemo2
{

    public static void main(String[] args)
    {

        Map<Integer, String> map = new LinkedHashMap<>();
        map.put(1, "Peter");
        map.put(2, "John");
        map.put(3, "Juli");
        map.put(4, "Stephan");

        /*
         * In Java 8, we can loop a Map with forEach + lambda
         * expression+multiple statements.
         */

        map.forEach((k, v) -> {
            System.out.println("key : " + k + " value : " + v);
            if ("John".equals(v))
            {
                System.out.println("Hello John");
            }
        });
    }

}
Output
key : 1 value : Peter
key : 2 value : John
Hello John
key : 3 value : Juli
key : 4 value : Stephan

Refer:
https://docs.oracle.com/javase/8/docs/api/index.html?java/util/Map.html

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

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

Bitbucket Link:
https://bitbucket.org/ramram43210/java/src/4c13bd19ff03c6acdc5e87d7803290d625ce640a/BasicJava/LambdaDemo_map_foreach_app/?at=master

See also:

  • All JavaEE Viedos Playlist
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  • All JAVA EE Links
  • Servlets Tutorial
  • All Design Patterns Links
  • JDBC Tutorial
  • Java Collection Framework Tutorial
  • JAVA Tutorial
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