Partially creating immutable object in java

Question

I have an immutable object which also has its builder class. I need a way to create the object in 2 phases where in first phase with a few parameters and in the other with rest. Is there any way or framework to do this?

Answer 1

You could either pass the builder to the second phase, or copy the data from the old object into a new object.

A good builder implementation will have a way of copying an object. For example with lombok, you can use the toBuilder option, which will create a builder from an existing object and allow you to create a new object with the data from the old object.

Answer 2

Here is my suggestion :

Follow Builder design pattern, Have two builders for each phase. I think that would be enough. I doubt there would be a framework for such things.

Answer 3

If you are following all the rules of an immutable object, you cannot do that.
The constructor is called only once per new .

Two possible ways are wrapping or using reflection .