package com.company;

import java.util.ArrayList;

public class Main {
    static ArrayList<Integer> CreateTestArray() {
        final int N = 100000000;
        ArrayList<Integer> testList = new ArrayList<>(N);
        for(int i = 0; i < N; ++i) {testList.add(i);}

        return testList;
    }

    static Integer GetFirstByStream(ArrayList<Integer> arrayList) {
        return arrayList.stream().findFirst().orElse(null);
    }

    static Integer GetFirstByMethod( ArrayList<Integer> arrayList) {
        if (!arrayList.isEmpty()) {
            return arrayList.get(0);
        }

        return null;
    }

    static void TestEmptyByStream() {
        ArrayList<Integer> integers = CreateTestArray();
        long startTime = System.currentTimeMillis();

        for (int i = 0; i < 100000; i++) {
            GetFirstByStream(integers);
        }

        long stopTime = System.currentTimeMillis();
        long elapsedTime = stopTime - startTime;
        System.out.println("By stream: " + elapsedTime + " ms");
    }

    static void TestEmptyByMethod() {
        ArrayList<Integer> integers = CreateTestArray();
        long startTime = System.currentTimeMillis();

        long total = 0;
        for (int i = 0; i < 100000; i++) {
            GetFirstByMethod(integers);
        }

        long stopTime = System.currentTimeMillis();
        long elapsedTime = stopTime - startTime;
        System.out.println("By method: " + elapsedTime + " ms");
    }

    public static void main(String[] args) {
        TestEmptyByStream();
        TestEmptyByMethod();
    }
}