EnumTest benchmark

Benchmark.java

/* EnumSet benchmark
 * $ javac Benchmark.java
 * $ java -ea Benchmark 
 * Ref: https://nullprogram.com/blog/2021/04/23/
 */
import java.util.Arrays;
import java.util.EnumSet;
import java.util.HashSet;
import java.util.Set;

public final class Benchmark {
    public static void main(String[] args) {
        for (int i = 0; i < 3; i++) {
            benchmarkHashSet();
            benchmarkEnumSet();
            benchmarkBitflags();
        }
    }

    static enum Flag { A, B, C, D, E, F, G }

    static void benchmarkEnumSet() {
        System.gc();
        var beg = System.nanoTime();
        Set<Flag> a = EnumSet.of(Flag.A, Flag.B, Flag.G);
        for (int i = 0; i < 1_000_000_000; i++) {
            Set<Flag> b = EnumSet.of(Flag.A, Flag.B, Flag.G);
            assert a.equals(b);
        }
        var end = System.nanoTime();
        System.out.println("EnumSet \t" + (end - beg)/1e9);
    }

    static void benchmarkHashSet() {
        System.gc();
        var beg = System.nanoTime();
        Set<Flag> a = new HashSet<>(Arrays.asList(Flag.A, Flag.B, Flag.G));
        for (int i = 0; i < 1_000_000_000; i++) {
            Set<Flag> b = new HashSet<>(Arrays.asList(Flag.A, Flag.B, Flag.G));
            assert a.equals(b);
        }
        var end = System.nanoTime();
        System.out.println("HashSet \t" + (end - beg)/1e9);
    }

    static final int A = 1 << 0;
    static final int B = 1 << 1;
    static final int C = 1 << 2;
    static final int D = 1 << 3;
    static final int E = 1 << 4;
    static final int F = 1 << 5;
    static final int G = 1 << 6;

    static void benchmarkBitflags() {
        System.gc();
        var beg = System.nanoTime();
        var a = A | B | G;
        for (int i = 0; i < 1_000_000_000; i++) {
            var b = A | B | G;
            assert a == b;
        }
        var end = System.nanoTime();
        System.out.println("bitfield\t" + (end - beg)/1e9);
    }
}