7- Predefined Functional Interfaces and Stream Coding Part

 

Predefined Functional Interfaces Coding Part

 Create a package with workable code with classes that  uses concepts of predefined functional interfaces(Consumer,Predicate and Supplier) and concepts of stream and Lamda expression

ConsumerDemo

package com.java.pre.functional.demo;

import java.util.Arrays;

import java.util.List;

import java.util.function.Consumer;

public class ConsumerDemo {

    public static void main(String[] args) {

        // Using consumer Interface

        Consumer<Integer> consumer = t -> System.out.println("Printing  : " + t);

        consumer.accept(10);

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

       

        // Using extension of Consumer Interface(forEach loop in stream)

        List<Integer> list1 = Arrays.asList(1, 2, 3, 4, 5);

       

list1.stream().forEach(t -> System.out.println("print  : " + t));

    }

}

CONSOLE

Printing  : 10

--------------------

print  : 1

print  : 2

print  : 3

print  : 4

print  : 5

---------------------------------------------

PredicateDemo

package com.java.pre.functional.demo;

import java.util.Arrays;

import java.util.List;

public class PredicateDemo {

   

    public static void main(String[] args) {

        List<Integer> list1 = Arrays.asList(1, 2, 3, 4, 5);

                     //Providing conditional check by using filter in stream(Extension of predicate demo)

        list1.stream().filter(t -> t % 2 == 0).forEach(t -> System.out.println("print  Even: " + t));

    }

}

CONSOLE

print  Even: 2

print  Even: 4

---------------------------------------------

SupplierDemo

package com.java.pre.functional.demo;

import java.util.Arrays;

import java.util.List;

public class SupplierDemo {

    public static void main(String[] args) {

        List<String> list1 = Arrays.asList();

                // Output without input is supplier interface(extension is orElseGet)

       

System.out.println(list1.stream().findAny().orElseGet(() -> "Hi ZeeK"));

    }

}

CONSOLE

Hi ZeeK