what is the functional difference between VoidVisitorAdapter and GenericVisitorAdapter in JavaParser

Question

what is the functional difference between VoidVisitorAdapter and GenericVisitorAdapter in JavaParser. I am using both , but they seem to provide the same functionality .

Answer 1

In short, the visit methods of a GenericVisitorAdapter instance can have a return value of type R, while those of a VoidVisitorAdapter can't.

public class MyVoidVisitor extends VoidVisitorAdapter<Void> {
    @Override
    public void visit(final ClassOrInterfaceDeclaration n, final Void arg) {
        // look into members
        super.visit(n, arg);
        // print the class name
        System.out.println(n.getNameAsString());
    }
}

public class MyGenericVisitor extends GenericVisitorAdaptor<List<String>, Void> {
    @Override
    public List<String> visit(final ClassOrInterfaceDeclaration n, final Void arg) {
        // look into members
        List<String> nestedClassNames = super.visit(n, arg);
        // accumulate the class name
        nestedClassNames.add(n.getNameAsString());
        return nestedClassNames;
    }
}

In the above example, the MyVoidVisitor can only print the class names into stdout because it doesn't have a return value. On the other hand, the MyGenericVisitor can accumulate nested class names into a list, which would then be returned to the caller.