Java Reflection: Getting fields and methods in declaration order

Question

Is there any way to get a classes declared fields (and methods) in the order of declaration using reflection? According to the documentation, the ordering of Methods and Fields returned by getFields(), getDeclaredFields(), etc. is undefined.

Specifying something like an index would be possible using annotation as suggested in Java reflection: Is the order of class fields and methods standardized?

Are there any better options, i.e. not having to specify the index manually?

Now before you ask what I need this for: we have a method that takes a quite big data structure as input and performs a lengthy calculation on it. To create unit tests, we made a method that takes an input object and an output instance and creates the Java source code (setting up input, invoking the calculation method, and asserting the correct results afterwards) as output. This code is much more readable when fields are written in declaration order.

Answer 1

With jdk 6, the reflected fields are in deed in their declaration order. In early jdk that wasn't the case. Apparently enough people have nagged.

Although not guaranteed by javadoc, I would still take this order as granted, and I assume the order will be kept in future jdks too.

In your app, like in most apps, the dependency on the declaration order is mostly vanity - your app won't fail if the order screws up, it just become a little uglier.