troubleshooting Question

Performance issue while iterating with streams

Avatar of srikotesh
srikotesh asked on
Java
5 Comments1 Solution109 ViewsLast Modified:
Hi Experts,

I have written the below program using java7 and java8

Collections are giving me result quickly when i compared with streams
Is any thing wrong in my code.
can some one suggest me what exactly the issue with streams iteration.

Collections is taking only 16 milliseconds
FROM STREAMS
localCaloricDishesName  [EggCurry, BeatRootCurry, LadyFinger]
109 millis

package com.java8;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class StreamAndFilter  {

	public static void main1(String[] args) {
		Long startTime = System.currentTimeMillis();	
		List<Dish> menu = new ArrayList<>();
		menu.add(new Dish("CarrotCurry",405));
		menu.add(new Dish("BeatRootCurry",215));
		menu.add(new Dish("PotatosCurry",450));
		menu.add(new Dish("TamatoCurry",500));
		menu.add(new Dish("LadyFinger",300));
		menu.add(new Dish("EggCurry",200));
		
		List<Dish> localCaloricDishesName = new ArrayList<>();
		
		for (Dish dish : menu) {
			if(dish.getCalories()<400){
				localCaloricDishesName.add(dish);
			}
		}
		
		Collections.sort(localCaloricDishesName,new Comparator<Dish>() {

			@Override
			public int compare(Dish o1, Dish o2) {
				// TODO Auto-generated method stub
				return Integer.compare(o1.getCalories(), o2.getCalories());
			}
			
		});
		
		List<String> curryNames = new ArrayList<String>();
		for (Dish dish : localCaloricDishesName) {
			curryNames.add(dish.getDishName());
		}
		
		System.out.println("curryNames"+curryNames);;
		System.out.println(System.currentTimeMillis()-startTime);
	}
	
	public static void main(String[] args) {
		System.out.println("FROM STREAMS");
		Long startTime = System.currentTimeMillis();
		List<Dish> menu = new ArrayList<>();
		menu.add(new Dish("CarrotCurry",405));
		menu.add(new Dish("BeatRootCurry",215));
		menu.add(new Dish("PotatosCurry",450));
		menu.add(new Dish("TamatoCurry",500));
		menu.add(new Dish("LadyFinger",300));
		menu.add(new Dish("EggCurry",200));
		
		List<String> localCaloricDishesName = 
				menu.stream()
				.filter(d->d.getCalories()<400)
				.sorted(Comparator.comparing(Dish :: getCalories))
				.map(Dish::getDishName)
				.collect(Collectors.toList());
		
		System.out.println("localCaloricDishesName  "+localCaloricDishesName);
		System.out.println(System.currentTimeMillis()-startTime);		
	}
}
ASKER CERTIFIED SOLUTION
CPColin
Senior Java Architect

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