AddTest.java

import java.math.BigDecimal;
import java.util.concurrent.TimeUnit;

import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.annotations.*;

@Warmup(iterations = 5, time = 3, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 10, time = 3, timeUnit = TimeUnit.SECONDS)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MILLISECONDS)
@Fork(2)
@State(Scope.Benchmark)
public class AddTest {
    long add(long sum) {
        int hash = hashCode();
        BigDecimal number = new BigDecimal(hash);
        sum += number.longValue();
        return sum;
    }

    long add1(long sum) {
        BigDecimal number = new BigDecimal(hashCode());
        sum += number.longValue();
        return sum;
    }

    @Benchmark
    public void testAdd(Blackhole bh) {
        long count = 100000000l;
        long sum = 0;
        for (long i=0; i<count; i++) {
            sum = add(sum);
        }
        bh.consume(sum);
    }

    @Benchmark
    public void testAdd1(Blackhole bh) {
        long count = 100000000l;
        long sum = 0;
        for (long i=0; i<count; i++) {
            sum = add1(sum);
        }
        bh.consume(sum);
    }
}

results.txt

Benchmark         Mode  Cnt     Score    Error  Units
AddTest.testAdd   avgt   20   214.740 ±  4.323  ms/op
AddTest.testAdd1  avgt   20  1138.269 ± 32.062  ms/op