MyBenchmark.java

package org.relgames;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public class MyBenchmark {

    @Benchmark
    public List<String> manualSort() {
        List<String> result = new ArrayList<>(6);
        List<String> list1 = list1();
        List<String> list2 = list2();
        Iterator<String> iterator1 = list1.iterator();
        Iterator<String> iterator2 = list2.iterator();
        String first = iterator1.next();
        String last = iterator2.next();
        for (int i = 0; i < list1.size() + list2.size(); i++) {
            if ((last == null || (first != null && first.compareTo(last) < 0))) {
                result.add(first);
                first = iterator1.hasNext() ? iterator1.next() : null;
            } else {
                result.add(last);
                last = iterator2.hasNext() ? iterator2.next() : null;
            }
        }

        return result;
    }

    @Benchmark
    public List<String> libSort() {
        List<String> result = new ArrayList<>(6);
        List<String> list1 = list1();
        List<String> list2 = list2();
        result.addAll(list1);
        result.addAll(list2);
        Collections.sort(result);
        return result;
    }

    private static final int N = 1000000;

    public List<String> list1() {
        List<String> result = new ArrayList<>(N);
        for (int i = 0; i < N; i++) {
            result.add(String.valueOf(i*2));
        }
        return result;
    }

    public List<String> list2() {
        List<String> result = new ArrayList<>(N);
        for (int i = 0; i < N; i++) {
            result.add(String.valueOf(i*2 + 1));
        }
        return result;
    }

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(MyBenchmark.class.getSimpleName())
                .forks(1)
                .build();

        new Runner(opt).run();
    }


}