JAVA EE: Static Method reference - Number less than 50| Method reference in Java 8

Thursday 15 June 2017

Static Method reference - Number less than 50| Method reference in Java 8 | Java method reference

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Static Method reference - Number less than 50| Method reference in Java 8 | Java method reference

Numbers.java

import java.util.ArrayList;
import java.util.List;
import java.util.function.Predicate;

class Numbers
{
    public static boolean isLessThanFifty(int number)
    {
        return number < 50;
    }

    public static List<Integer> findNumbers(List<Integer> list,
                                                Predicate<Integer> p)
    {
        List<Integer> newList = new ArrayList<>();
        for (Integer i : list)
        {
            /*
             * test the number is less than 50
             * then add to the newList.
             */
            if (p.test(i))
            {
                newList.add(i);
            }
        }
        return newList;
    }
}

LambdaDemo.java

import java.util.Arrays;
import java.util.List;
import java.util.function.Predicate;

public class LambdaDemo
{
    public static void main(String[] args)
    {

        List<Integer> list = Arrays.asList(12, 55, 75, 88, 24, 40);

        // Using an anonymous class
        List<Integer> listOfLessthanfiftyNumbers = Numbers.findNumbers(list, new Predicate<Integer>()
        {
            public boolean test(Integer i)
            {
                return Numbers.isLessThanFifty(i);
            }
        });
        
        System.out.println("listOfLessthanfiftyNumbers - anonymous class = "+listOfLessthanfiftyNumbers);
        
        // Using a lambda expression
        listOfLessthanfiftyNumbers = Numbers.findNumbers(list, (i) -> Numbers.isLessThanFifty(i));
        System.out.println("listOfLessthanfiftyNumbers - lambda expression = "+listOfLessthanfiftyNumbers);
        
        // Using a method reference
        listOfLessthanfiftyNumbers = Numbers.findNumbers(list, Numbers::isLessThanFifty);
        System.out.println("listOfLessthanfiftyNumbers - method reference = "+listOfLessthanfiftyNumbers);
    }

}

Output

listOfLessthanfiftyNumbers - anonymous class = [12, 24, 40]
listOfLessthanfiftyNumbers - lambda expression = [12, 24, 40]
listOfLessthanfiftyNumbers - method reference = [12, 24, 40]