These days there is some Machinery in the JVM for creating truly anonymous classes that can be garbage collected (https://docs.oracle.com/en/java/javase/22/docs

These days there is some Machinery in the JVM for creating truly anonymous classes that can be garbage collected (https://docs.oracle.com/en/java/javase/22/docs/api/java.base/java/lang/invoke/MethodHandles.Lookup.html#defineHiddenClass(byte%5B%5D,boolean,java.lang.invoke.MethodHandles.Lookup.ClassOption https://docs.oracle.com/en/java/javase/22/docs/api/java.base......) ), but they are trickier to generate as they can’t have static fields (you don’t have a class name so have no way to refer to them) etc.