What is the difference between defining @Transactional on class vs method

Question

Case1

@Transactional
public class UserServiceImpl implements UserService {

    ...................
    public void method1(){
        try{
                    


        

Answer 1

Quoting from here

The Spring team's recommendation is that you only annotate concrete classes with the @Transactional annotation, as opposed to annotating interfaces.

Since this mechanism is based on proxies, only 'external' method calls coming in through the proxy will be intercepted. This means that 'self-invocation', i.e. a method within the target object calling some other method of the target object, won't lead to an actual transaction at runtime even if the invoked method is marked with @Transactional!