Jersey client: How to add a list as query parameter

@GET does support List of Strings

Setup:
Java : 1.7
Jersey version : 1.9

Resource

@Path("/v1/test")

Subresource:

// receive List of Strings
@GET
@Path("/receiveListOfStrings")
public Response receiveListOfStrings(@QueryParam("list") final List<String> list){
    log.info("receieved list of size="+list.size());
    return Response.ok().build();
}

Jersey testcase

@Test
public void testReceiveListOfStrings() throws Exception {
    WebResource webResource = resource();
    ClientResponse responseMsg = webResource.path("/v1/test/receiveListOfStrings")
            .queryParam("list", "one")
            .queryParam("list", "two")
            .queryParam("list", "three")
            .get(ClientResponse.class);
    Assert.assertEquals(200, responseMsg.getStatus());
}

If you are sending anything other than simple strings I would recommend using a POST with an appropriate request body, or passing the entire list as an appropriately encoded JSON string. However, with simple strings you just need to append each value to the request URL appropriately and Jersey will deserialize it for you. So given the following example endpoint:

@Path("/service/echo") public class MyServiceImpl {
    public MyServiceImpl() {
        super();
    }

    @GET
    @Path("/withlist")
    @Produces(MediaType.TEXT_PLAIN)
    public Response echoInputList(@QueryParam("list") final List<String> inputList) {
        return Response.ok(inputList).build();
    }
}

Your client would send a request corresponding to:

GET http://example.com/services/echo?list=Hello&list=Stay&list=Goodbye

Which would result in inputList being deserialized to contain the values 'Hello', 'Stay' and 'Goodbye'

i agree with you about alternative solutions which you mentioned above

1. Use POST instead of GET;
2. Transform the List into a JSON string and pass it to the service.

and its true that you can't add List to MultiValuedMap because of its impl class MultivaluedMapImpl have capability to accept String Key and String Value. which is shown in following figure

still you want to do that things than try following code.

Controller Class

package net.yogesh.test;

import java.util.List;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;

import com.google.gson.Gson;

@Path("test")
public class TestController {
       @Path("testMethod")
       @GET
       @Produces("application/text")
       public String save(
               @QueryParam("list") List<String> list) {

           return  new Gson().toJson(list) ;
       }
}

Client Class

package net.yogesh.test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.ws.rs.core.MultivaluedMap;

import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.core.util.MultivaluedMapImpl;

public class Client {
    public static void main(String[] args) {
        String op = doGet("http://localhost:8080/JerseyTest/rest/test/testMethod");
        System.out.println(op);
    }

    private static String doGet(String url){
        List<String> list = new ArrayList<String>();
        list = Arrays.asList(new String[]{"string1,string2,string3"});

        MultivaluedMap<String, String> params = new MultivaluedMapImpl();
        String lst = (list.toString()).substring(1, list.toString().length()-1);
        params.add("list", lst);

        ClientConfig config = new DefaultClientConfig();
        com.sun.jersey.api.client.Client client = com.sun.jersey.api.client.Client.create(config);
        WebResource resource = client.resource(url);

        ClientResponse response = resource.queryParams(params).type("application/x-www-form-urlencoded").get(ClientResponse.class);
        String en = response.getEntity(String.class);
        return en;
    }
}

hope this'll help you.