JAVA EE: How to find the sum of all the product price using Collectors method of Java 8 Stream

Wednesday 12 July 2017

How to find the sum of all the product price using Collectors method of Java 8 Stream

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https://www.youtube.com/watch?v=ZNsO7A3D4oU&list=UUhwKlOVR041tngjerWxVccw

Product.java

class Product
{
    private int id;
    private String name;
    private int price;

    public Product(int id, String name, int price)
    {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
    }

    public int getId()
    {
        return id;
    }

    public void setId(int id)
    {
        this.id = id;
    }

    public String getName()
    {
        return name;
    }

    public void setName(String name)
    {
        this.name = name;
    }

    public int getPrice()
    {
        return price;
    }

    public void setPrice(int price)
    {
        this.price = price;
    }

    @Override
    public String toString()
    {
        return "Product [id=" + id + ", name=" + name + ", price="
                + price + "]";
    }

}

StreamDemo.java

import java.util.ArrayList;
import java.util.List;
import java.util.LongSummaryStatistics;
import java.util.stream.Collectors;
/**
 * 
 * Sum by using Collectors Methods.
 *
 */
public class StreamDemo
{
    public static void main(String[] args)
    {
        List<Product> productList = new ArrayList<Product>();

        // Adding Products
        productList.add(new Product(1, "Sony mobile", 25000));
        productList.add(new Product(2, "Lenovo mobile", 15000));
        productList.add(new Product(3, "Nokia mobile", 10000));
        productList.add(new Product(4, "Samsung mobile", 40000));

        
        /*
         * Using Collectors's method to sum the prices.  
         */     
        LongSummaryStatistics longSummaryStatistics = productList.stream() 
                 .collect(Collectors.summarizingLong((product->product.getPrice())));  
    
        System.out.println(longSummaryStatistics);  
        System.out.println("Count = "+longSummaryStatistics.getCount());
        System.out.println("Sum = "+longSummaryStatistics.getSum());  
        System.out.println("Max Price = "+longSummaryStatistics.getMax());  
        System.out.println("Min Price = "+longSummaryStatistics.getMin());
        System.out.println("Average Price = "+longSummaryStatistics.getAverage());  
                
    }
}

Output

LongSummaryStatistics{count=4, sum=90000, min=10000, average=22500.000000, max=40000}
Count = 4
Sum = 90000
Max Price = 40000
Min Price = 10000
Average Price = 22500.0