Stream can be consumed only once

package lambdasinaction.chap4;

import java.util.*;
import java.util.stream.*;
import static java.util.stream.Collectors.toList;


public class stream {

    public static void main(String...args){
        List<String> names = Arrays.asList("Java8", "Lambdas", "In", "Action");
        Stream<String> s = names.stream();
        s.forEach(System.out::println);
        // uncommenting this line will result in an IllegalStateException
        // because streams can be consumed only once
        s.forEach(System.out::println);
    }
}

Shopping Cart Checkout using java8

package com.checkout.shoppingcart;

import java.math.BigDecimal;

import java.util.List;

import java.util.Map;

import static java.util.stream.Collectors.counting;

import static java.util.stream.Collectors.partitioningBy;

//Below is an example of shopping cart example using java8

public class ShoppingCartExampleJava8 {

    private static final int ORANGES_TO_DISCOUNT = 3;

    private static final int APPLES_TO_DISCOUNT = 2;

    enum Fruit {

        APPLE(new BigDecimal("00.60")),ORANGE(new BigDecimal("00.25"));

        private BigDecimal cost;

        Fruit(BigDecimal cost) {

            this.cost=cost;

        }

    }

    private List<Fruit> fruits;

    ShoppingCartExampleJava8(List<Fruit> fruits) {

        this.fruits=fruits;

    }

    public BigDecimal getTotalBill() {

        BigDecimal totalBills  = new BigDecimal("0.00");

        Map<Boolean,Long> partitionFruits =

                fruits.stream()

                        .collect(

                                partitioningBy( fruit -> fruit.equals(Fruit.APPLE),

                                        counting()));

        long totalApples = partitionFruits.get(true);

        long totalOranges = partitionFruits.get(false);

        return totalBills.add(getApplesCost(totalApples)).add(getOrangesCost(totalOranges));

    }

    private BigDecimal getOrangesCost(long countOranges) {

        long orangesToDiscount = countOranges / ORANGES_TO_DISCOUNT;

        long totalOrangesToCharge = (orangesToDiscount*2) + (countOranges%ORANGES_TO_DISCOUNT);

        return new BigDecimal(Long.valueOf(totalOrangesToCharge)).multiply(Fruit.ORANGE.cost);

    }

    private BigDecimal getApplesCost(long countApple) {

        long appletodiscount = countApple / APPLES_TO_DISCOUNT;

        long totalApplestoCharge = appletodiscount + (countApple%APPLES_TO_DISCOUNT);

        return new BigDecimal(Long.valueOf(totalApplestoCharge)).multiply(Fruit.APPLE.cost);

    }

}