What I want to do is, updating a customer if it is present but if there is no customer then throw an exception. But I could not find the correct stream function to do that. How can I achieve this ?

public Customer update(Customer customer) throws Exception {
        Optional<Customer> customerToUpdate = customerRepository.findById(customer.getId());
        customerToUpdate.ifPresentOrElse(value -> return customerRepository.save(customer),
        throw new Exception("customer not found"));
    }

I could not return the value coming from save function because it is saying that it is void method and not expecting return value.

CodePudding user response：

As Guillaume F. already said in the comments, you could just use orElseThrow here:

Customer customer = customerRepository.findById(customer.getId())
    .orElseThrow(() -> new Exception("customer not found"));
return customerRepository.save(customer);

By the way, avoid throwing Exception, as that exception is too broad. Use a more specific type, like NotFoundException.

CodePudding user response：

public Comment getCommentById(long id) {
        Optional<Comment> optional = commentRepository.findById(id);
        Comment comments = null;
        if(optional.isPresent()){
            comments = optional.get();
        }else{
            throw new RuntimeException("Post not found for id :: "   id);
        }
        return comments;
    }

Above is the code snippet from one of my project you can try in this way.