Question

HttpEntity<?> requestEntity = new HttpEntity<Object>(json, headers);

I have a couple of questions here?

1. What does the ? mean here. Why have they put <?> instead of <Object>
2. Why does the HTTPEntity Constructor take <Object> as its type but the Class Reference taking <?> as its type.

Answer 1

?— wildcard syntax

HttpEntity<?> requestEntity = new HttpEntity<Object>(json, headers);

`HttpEntity<?>` whose element type matches anything..

Remember that if you try to add Object into requestEntity you’d get a compiler error.

       requestEntity.add(new Object());//compiler error on this line as it expects `?` not an object

read about generics here