bench a few ways to sort a Map. Especially compare speed of TreeMap vs sorted Streams

MapSortTest

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package at.rise.docarchive;

import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.TimeUnit;

import org.junit.Test;

import static org.junit.Assert.assertEquals;

/**
 * turned out TreeMap is still 20% faster than sorted Stream.
 *
 * @author <a href="mailto:[email protected]">Mark Struberg</a>
 */
public class MapSortTest {

    private final static int ITERATIONS = 5_000_000;

    private static Map<String, String> vals = new HashMap<>();
    static {
      vals.put("a", "b");
      vals.put("2a", "sdfb");
      vals.put("d", "sdfb");
      vals.put("3wjehrwa", "sdfb");
      vals.put("2a", "sdfb");
      vals.put("wglkjöa", "sdfb");
      vals.put("elkasdfa", "sdfb");
      vals.put("fasdfa", "sdfb");
      vals.put("xfafasa", "sdfb");
      vals.put("faasdf", "sdfb");
      vals.put("3fasdfa", "sdfb");
      vals.put("2xfafasa", "sdfb");
      vals.put("4faasdf", "sdfb");
    };

    @Test
    public void testSameResult() {
        String vT = sortTreeMap(vals);
        String vS = sortStream(vals);
        assertEquals(vT.length(), vS.length());
    }

    @Test
    public void testMap() {
        long totalsize = 0L;
        // warmup
        for (int i=0; i<1000; i++) {
            totalsize += sortTreeMap(vals).length();
        }

        totalsize = 0L;

        long start = System.nanoTime();
        for (int i=0; i<ITERATIONS; i++) {
            totalsize += sortTreeMap(vals).length();
            //X totalsize += sortStream(vals).length();
        }
        long end = System.nanoTime();

        System.out.println(totalsize + "took " + TimeUnit.NANOSECONDS.toMillis(end - start));
    }

    private String sortTreeMap(Map<String, String> val) {
        TreeMap<String, String> sorted = new TreeMap<>(val);
        StringBuilder sb = new StringBuilder(2048);
        for (Map.Entry<String, String> e : sorted.entrySet()) {
            sb.append(e.getKey()).append('=').append(e.getValue()).append(';');
        }
        return sb.toString();
    }

    private String sortStream(Map<String, String> val) {
        StringBuilder sb = new StringBuilder(2048);

        val.entrySet().stream()
                .sorted(Map.Entry.comparingByKey())
                .forEach(e -> sb.append(e.getKey()).append('=').append(e.getValue()).append(';'));
        return sb.toString();
    }
}