Persisting Lambdas/Functions

[tschuehly]

I want to persist a Function using EclipseStore. It is persisted successfully:

But when restarting the application I get the following exception:

Caused by: org.eclipse.serializer.persistence.exceptions.PersistenceException: Missing runtime type for required type handler for type: io.alanda.davinci.datagenerator.AddressGenerator$$Lambda/0x00007ff0021d7408

How can I get this to work? Thank you for your help!
@hg-ms @fh-ms

[fh-ms]

Unfortunately, you can not.

While, in theory, Lambdas are serializable, the JVM cannot guarantee that they will be restored properly because they don't have a unique name like classes but just contiguous numbers.

For example given following code

class Foo
{
    Consumer<String> printer = System.out::println;
}

If you store an instance of Foo, then change the code to this:

class Foo
{
    void someCode()
    {
        Consumer<String> something = (str) -> someAction(str);
    }


    Consumer<String> printer = System.out:println;
}

After restoring the Foo instance, the value for printer would be the something function because it has the first position in the code now.

It doesn't work with the built-in Java serializer as well.

https://docs.eclipsestore.io/manual/storage/addendum/supported-java-features.html#_java_8