ClassCastException: cannot assign SerializedLambda to field with ClassLoader

Chris Hegarty chris.hegarty at
Tue Mar 26 09:07:19 UTC 2019

> On 26 Mar 2019, at 07:54, Peter Levart <peter.levart at> wrote:
> Hi Seth,
> I think you stumbled on a "defect" of Java Serialization mechanism. Namely, the inability for it to correctly deserialize object graphs containing a cycle when an object in such cycle uses the "readResolve()" special method to replace the deserialized object with a replacement object. SerializedLambda is a class with instances that are 1st deserialized from stream then "replaced" with real lambda objects via the "readResolve()" method which constructs and returns the "real" lambda object. The deserialized SerializedLambda object is nevertheless attempted to be (temporarily) assigned to the field that would hold the final lambda object, which fails as the filed is of different type than SerializedLambda (or supertype).
> You can check my claims by changing the type of the field holding the lambda to java.lang.Object and see if it works... (It should if my memory serves me well :-)
> This is a known defect of Java serialization and is not specific to serialized lambda.

Correct. Cycles in the object graph can be problematic when mixed with
Serializable classes that have a readResolve method or the follow the
Serialization Proxy Pattern. The Immutable Collection implementations
are another such example.

I see David pointed to some specific unresolved issues relating to
Serializable lambdas. I haven't looked into them.


More information about the core-libs-dev mailing list