Instance field may not be initialized by 'readObject()'

Reports fields that are not guaranteed to be initialized after the object is deserialized by the readObject() method.

The inspection doesn't report transient fields.

Note: This inspection uses a very conservative control flow algorithm, and may incorrectly report fields as uninitialized.

Example:

class DataObject implements Serializable {
  String s; // s is not initialized in readObject
  int i;

  private void readObject(ObjectInputStream stream) throws IOException {
    i = stream.readInt();
  }
}

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.

InstanceVariableMayNotBeInitializedByReadObject

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 InstanceVariableMayNotBeInitializedByReadObject

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