SEVERE: A message body writer for Java class java.util.ArrayList and MIME media type application/json was not found

Question

I am testing RESTful services and when I execute I am getting exceptions although I have the following jars in my class path(WEB-INF/lib), I am not using Maven and my JDK version is 1.5. Other questions regarding this issue didn't help to resolve the problem. Code snippet ``` @GET @Produces("application/json") //@Produces({MediaType.APPLICATION_JSON}) tried this, didn't work either public List getEmployees() { List empList = myDAO.getAllEmployees(); log.info("size " + empList.size()); return empList; } @XmlRootElement public class Emp { ...... ``` web.xml ```

Jersey Web Application

com.sun.jersey.spi.container.servlet.ServletContainer

com.sun.jersey.config.property.packages

test.employees

com.sun.jersey.api.json.POJOMappingFeature

true

Accepted Answer

Make sure you don't have multiple Jersey versions in your project. From the list you provided there are modules from 3 different versions (1.2, 1.10, 1.8). For some modules Jersey does a check that the version of a module is the same as the version of the core. If it's not then providers of the module (such as MessageBodyReaders, MessageBodyWriters) are not registered in the runtime. This can be problem in your setup - json vs core (1.8 vs 1.2).

SEVERE: A message body writer for Java class java.util.ArrayList and MIME media type application/json was not found

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