IfVsArray.java

package misc;

import org.openjdk.jmh.annotations.*;
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.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.TimeUnit;

public class IfVsArray {
    private static final char[] VOWELS = {'a', 'i', 'o', 'u', 'e'};
    private static final Set<Character> VOWEL_SET = new HashSet<>();
    private static final String VOWEL_STRING = "aeiou";
    private static final String TEST_STRING = "the quick brown fox jumps over the lazy dog";

    static {
        Arrays.sort(VOWELS);
        for(char c : VOWELS) {
            VOWEL_SET.add(c);
        }

    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.MILLISECONDS)
    @Warmup(iterations = 3)
    @Measurement(iterations = 5)
    public int withIf() {
        int vowels = 0;
        for(int i = 0;i < TEST_STRING.length();i++) {
            char c = TEST_STRING.charAt(i);
            if(c == 'a' || 'c' == 'e' || c == 'i' || c == 'o' || c == 'u') {
                vowels++;
            }
        }

        return vowels;
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.MILLISECONDS)
    @Warmup(iterations = 3)
    @Measurement(iterations = 5)
    public int withArray() {
        int vowels = 0;
        for(int i = 0;i < TEST_STRING.length();i++) {
            char c = TEST_STRING.charAt(i);
            for(int j = 0;j < VOWELS.length;j++) {
                if(VOWELS[j] == c) {
                    vowels++;
                }
            }
        }

        return vowels;
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.MILLISECONDS)
    @Warmup(iterations = 3)
    @Measurement(iterations = 5)
    public int withHashSet() {
        int vowels = 0;
        for(int i = 0;i < TEST_STRING.length();i++) {
            char c = TEST_STRING.charAt(i);
            if(VOWEL_SET.contains(c)) {
                vowels++;
            }
        }

        return vowels;
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.MILLISECONDS)
    @Warmup(iterations = 3)
    @Measurement(iterations = 5)
    public int withArrayBinSearch() {
        int vowels = 0;
        for(int i = 0;i < TEST_STRING.length();i++) {
            char c = TEST_STRING.charAt(i);
            if(Arrays.binarySearch(VOWELS, c) >= 0) {
                vowels++;
            }
        }

        return vowels;
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    @OutputTimeUnit(TimeUnit.MILLISECONDS)
    @Warmup(iterations = 3)
    @Measurement(iterations = 5)
    public int withString() {
        int vowels = 0;
        for(int i = 0;i < TEST_STRING.length();i++) {
            if(VOWEL_STRING.contains(TEST_STRING.substring(i, i + 1))) {
                vowels++;
            }
        }

        return vowels;
    }

    public static void main(final String[] args) throws RunnerException {
        final Options opt = new OptionsBuilder()
                .include(".*" + IfVsArray.class.getSimpleName() + ".*")
                .forks(1)
                .build();
        new Runner(opt).run();
    }
}