JavaVisitor vs. JavaIsoVisitor: When to use what?

Question

I wonder, what the difference between JavaVistitor and JavaIsoVisittor is. When shall I use what. This is not clear to me from the documentatio https://docs.openrewrite.org/.

Answer 1

Did you see the JavaDoc at the top of the JavaIsoVisitor?

/**
 * This iso(morphic) refactoring visitor is the appropriate base class for most Java refactoring visitors.
 * It comes with an additional constraint compared to the non-isomorphic JavaRefactorVisitor:
 * Each visit method must return an AST element of the same type as the one being visited.
 *
 * For visitors that do not need the extra flexibility of JavaRefactorVisitor, this constraint
 * makes for a more pleasant visitor authoring experience as less casting will be required.
 */
public class JavaIsoVisitor<P> extends JavaVisitor<P> {

So whenever you're only replacing elements with elements of the same type, you're able to use the JavaIsoVisitor.

When you're replacing elements with one or more element of a different type, you will have to use JavaVisitor.