ObjectMapper - writeValueAsString method converts object to null

Question

I have this object:

dataToPost = {"input":{"key":"value"}}

when I process it at this line:

String data = mapper.writeValueAsString(dataToPost);

It returns the following:

{"input":"null"}

Why is it set to null? How to fix this?

Answer 1

要将jackson对象转换为String ，可以使用，

String data= dataToPost.toString();