Non-serializable object passed to 'ObjectOutputStream'

Reports non-Serializable objects used as arguments to java.io.ObjectOutputStream.write(). Such calls will result in runtime exceptions.

This inspection assumes objects of the types java.util.Collection and java.util.Map to be Serializable, unless the types they are declared in are non-Serializable.

Example:

  public class IWantToSerializeThis {
    public static void main(String[] args) throws IOException {
      try(var stream = new ObjectOutputStream(Files.newOutputStream(Paths.get("output")))) {
        // Warning -- will fail with NotSerializableException
        stream.writeObject(new IWantToSerializeThis());
      }
    }
  }

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

NonSerializableObjectPassedToObjectStream

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Java | Serialization issues

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection NonSerializableObjectPassedToObjectStream

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.2

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.2, Qodana for JVM 2025.2,

Last modified: 18 September 2025