How does serialization performance compare between `long` and `double` in Java?

General Discussions
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1

Both long and double take 8 bytes in Java, and while double offers a wider range for storing whole numbers, long might still be sufficient for many use cases. How does java long vs double serialization and deserialization performance compare? Also, does checking if a value is integer impact this choice?

2

I’ve worked on performance tuning for about 5 years, and benchmarking tells you more than assumptions ever will.

So instead of guessing which is faster in the java long vs double debate, let’s just test it. I used Java’s built-in ObjectOutputStream and ObjectInputStream to serialize both long and double. Here’s the benchmark I ran:

// Java Serialization Benchmark using Object Streams
// ...
// [Include your original SerializationBenchmark code here]

:mag: What I observed:

  • long serialized just a bit faster than double
  • Likely because double has more complexity due to its floating-point structure
  • If you’re dealing strictly with integers, long wins on simplicity and speed.
3

Been optimizing serialization pipelines in Java for over a decade — and yeah, the built-in serialization is bulky.

Tom’s approach is solid, but here’s a slight tweak if performance is really critical. Java’s default serialization comes with a lot of overhead. If you want raw speed in the java long vs double performance test, ditch ObjectOutputStream and try DataOutputStream.

// Java Serialization Benchmark using DataOutputStream
// ...
// [Include your original DataOutputStreamTest code here]

:sparkles: Why this matters:

  • DataOutputStream writes pure bytes — no class metadata, no bloat.
  • It’s snappier and more predictable.
  • long still edges out double, but the margin is tighter now. When you need high-throughput data serialization, this lightweight approach is the way to go.
4

Worked on data processing pipelines handling millions of records daily — subtle type choices like this matter more than you think.

Just wanted to add something here — if you’re storing integer values inside a double, maybe rethink that choice. It’s common, especially when data comes from JSON or external APIs. But in the java long vs double performance story, this can bite you later.

Here’s a quick check to see if a double is really just a long in disguise:

// Fast Integer Check for Doubles
public class DoubleIntegerCheck {
    public static void main(String[] args) {
        double value = 12345.0;
        boolean isInteger = value == Math.floor(value) && !Double.isInfinite(value);
        System.out.println("Is integer: " + isInteger);
    }
}

:bulb: Why this helps:

  • It’s super fast (O(1)), but do it millions of times and it adds up.
  • If your dataset mostly holds whole numbers, switching to long might not only be cleaner — it’s faster to serialize too.