How to get type and generic type from javax.lang.model.VariableElement?

Question

I'm using annotation processing and javapoet library to generate some source code.

Say, I've a

VariableElement fieldElement

and if

System.out.println("type:- " + fieldElement.asType().toString());

prints

type:- java.util.Set<com.example.demo.test.model.User>

How do I get the Set class and User class so I can do something like this with javapoet?

ClassName user = ClassName.get("com.example.demo.test.model", "User");
ClassName set = ClassName.get("java.util", "Set");
TypeName setOfUsers = ParameterizedTypeName.get(set, user);

Some string comparison would get the job done, but doesn't seem like the ideal approach.

Sagar Gangwal · Accepted Answer · 2020-08-16 17:52:30Z

2

You can try below code.

For getting that User class you can use fieldElement.getEnclosingElement(), it will give you class name with full package name.

Now if you want only name of that class you can use enclosingElement.getSimpleName().

And to get enclosedByElement you can use TypeSymbol.Simply cast fieldElement.asType() to Type and get tsym attribute.

        VariableElement fieldElement;

        Symbol.TypeSymbol containerForEnclosingElement=((Type)fieldElement.asType()).tsym;
        Element enclosingElement=fieldElement.getEnclosingElement();

        System.out.println("containerForEnclosingElement:- " +  containerForEnclosingElement);
        System.out.println("enclosingElement:- " +  enclosingElement);
        System.out.println("enclosingElement Name:- " +  enclosingElement.getSimpleName());
        System.out.println("fieldElement without root Type:- "+((Type) fieldElement.asType()).getTypeArguments().get(0));

Above code will print output as below.

containerForEnclosingElement:- java.util.Set
enclosingElement:- com.example.demo.test.model.User.
enclosingElement Name:- User
fieldElement without root Type:- com.example.demo.test.model.User

You can also create one Utility method to get this two values.

This will help you.

edited Aug 16, 2020 at 17:52

answered Aug 16, 2020 at 16:38

Sagar Gangwal

8,1303 gold badges28 silver badges45 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Drunken Daddy Over a year ago

fieldElement.getEnclosingElement() is not giving User. I've Set<User> users as a private variable in another class. It is giving me the another class. Also, from what package does Symbol.TypeSymbol come from?

Sagar Gangwal Over a year ago

import com.sun.tools.javac.code.Symbol; You can import this.

Sagar Gangwal Over a year ago

If you see my next line fieldElement.getEnclosingElement().getSimpleName(), you will get idea.

Drunken Daddy Over a year ago

as I said fieldElement.getEnclosingElement().getSimpleName() is also returning the name of the class in which Set<User> users is a private field. And getting cannot resolve symbol .tsym after importing com.sun.tools.javac.code.Symbol;

Drunken Daddy Over a year ago

I've teamviewer.

|

Collectives™ on Stack Overflow

How to get type and generic type from javax.lang.model.VariableElement?

1 Answer 1

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related