java - Mockito and string objects

I've started playing around with mockito today and I've encountered a problem. This is the class I'm trying to create test cases on:

@Path("search")
public class SearchWebService {

private static final Logger logger = Logger.getLogger(SearchWebService.class);

@EJB

UserServiceInterface userService;

@GET
@Path("/json/{searchstring}")
@Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
@RolesAllowed("User")
public List getJSONFromSearchResults(@PathParam("searchstring") String searchString, @Context HttpServletRequest request) {
    logger.info("getJSONFromSearchResults called");

    //Users own email

    String ownemail = request.getRemoteUser();

    if (searchString.contains(" ")) {
        //Split String in two at first space
        String names[] = searchString.split("\\s+", 2);

        List userList = userService.searchByFullName(names[0], names[1], ownemail);
        if (userList.size() > 0) {
            return userList;
        } //Check for cases where the last name contains spaces

        else {
            return userService.searchByLastName(searchString, ownemail);
        }
    }
    return userService.searchBySingleName(searchString, ownemail);
}
}

I'm at searchString.contains(" ") and I'm trying to invoke "when(...).thenReturn(...)" But mockito throws an exception saying that "Cannot mock/spy class java.lang.String" I'm not sure I'm doing it correctly when testing this web service. Maybe there is some otherway to do this? Here is my test class:

public class SearchWebServiceTest {

@Mock
UserServiceInterface mockedUserService;
@Mock
Logger mockedLogger;
@Mock
HttpServletRequest mockedRequest;
@Mock

String mockedString;
@Mock
List mockedUserList;

@Before
public void setUp() throws Exception {
    MockitoAnnotations.initMocks(this);
}

@Test

public void testGetJSONFromSearchResultsSpace() throws Exception {
    when(mockedRequest.getRemoteUser()).thenReturn("email");
    when("StringWithSpace".contains(" ")).thenReturn(true);
    when("StringWitchSpace".split("\\s+", 2)).thenReturn(null);
    when(mockedUserService.searchByFullName("name1", "name2", "email")).thenReturn(mockedUserList);
    assertTrue(mockedUserList.size() > 0);
}

Answer

you cannot mock final classes (like String). This is a known limitation of the framework.

You can refer this link.

Mockito Verification Not Failing

I hope it helps !!!