1.      Java Stream Example : reduce() Method in Collection

2.      Java Stream Example: Sum by using Collectors Methods

3.      Java Stream Example: Find Max and Min Product Price

4.      Java Stream Example: count() Method in Collection

package streamconcept;

public class ConsumerProduct {

               

                int cpId;

                String cpName;

                float cpprice;

                public ConsumerProduct(int cpId, String cpName, float cpprice) {

                                super();

                                this.cpId = cpId;

                                this.cpName = cpName;

                                this.cpprice = cpprice;

                }

               

               

}

package streamconcept;

import java.util.ArrayList;

import java.util.List;

import java.util.stream.Collectors;

public class ConsumerProductMain {

               

                public static void main(String[] args) {

                                List<ConsumerProduct> l=new ArrayList<>();

                                ConsumerProduct cp1=new ConsumerProduct(101, "cooler", 15000.00f);

                                ConsumerProduct cp2=new ConsumerProduct(102, "laptop", 45000.00f);

                                ConsumerProduct cp3=new ConsumerProduct(103, "mobile", 10000.00f);

                                ConsumerProduct cp4=new ConsumerProduct(104, "ac", 19000.00f);

                                ConsumerProduct cp5=new ConsumerProduct(105, "inverter", 30000.00f);

                                l.add(cp1);

                                l.add(cp2);

                                l.add(cp3);

                                l.add(cp4);

                                l.add(cp5);

                               

                                System.out.println("-------summation of all price ist way-----------");

                               

                                //ist way

                               

                                float totalprice=l.stream()

                                                                .map(p->p.cpprice)

                                                                .reduce(0.0f,(sum,price)->sum+price);  // accumulating price 

                                        System.out.println(totalprice);

                                       

                                        System.out.println("-------summation of all price 2nd way-----------");

                                        //2nd way

                                       

                                        float totalprice1=l.stream()

                                                                .map(p->p.cpprice)

                                                                .reduce(0.0f, Float::sum);// accumulating price, by referring method of Float class

                                        System.out.println(totalprice1);

                                       

                                        System.out.println("-------summation of all price 3rd way-----------");

                                        //3rd way

                                       

                                        double totalprice2=l.stream()

                                                                .collect(Collectors.summingDouble(p->p.cpprice));

                                        System.out.println(totalprice2);

                                       

                                        //find maximum price and minimum price

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

                                       ConsumerProduct maxprice = l.stream()

                                        .max((p1,p2)->

                                        p1.cpprice>p2.cpprice?1:-1).get();

                                       System.out.println(maxprice.cpprice);

                                      

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

                                       ConsumerProduct minprice = l.stream()

                                                                        .min((p1,p2)->

                                                                        p1.cpprice<p2.cpprice?-1:1).get();

                                                                       System.out.println(minprice.cpprice);

                                                                      

                                                                      

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

                                                                      long count =l.stream()

                                                                                                  .filter(p->p.cpprice<=15000.00f)

                                                                                                  .count();

                                                                      System.out.println(count);

                                      

                                       

                                       

                                       

                                       

                                                               

                               

                }

}

o/p:--------------------

-------summation of all price ist way-----------

119000.0

-------summation of all price 2nd way-----------

119000.0

-------summation of all price 3rd way-----------

119000.0

-----maximum price--------------

45000.0

-----minimum price--------------

10000.0

--------------count() demo--------

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