I\'m considering using Java for a large project but I haven\'t been able to find anything that remotely represented structures in Java. I need to be able to convert network
ByteBuffer.wrap(new byte[] {}).getDouble();
There is nothing which matches your description.
The closest thing to a struct in Java is a simple class which holds values either accessible through it's fields or set/get methods.
The typical means to convert between Java class instances and on-the-wire representations is Java serialization which can be heavily customized as need be. It is what is used by Java's Remote Method Invocation API and works extremely well.