title: invalid hexadecimal representation of an ObjectId in Mongo DB Rest API
body: <p>I am using REST API to fetch data using @Form param from Mongo DB and got the exception: 'Invalid hexadecimal representation of ObjectId'. The syntax seems to be correct, not sure whats going wrong there. I am passing new ObjectId (id) in the rest parameter. The code is as below:</p>
  
  <pre><code>//Country.java
  
  package com.speed.infoaxon;
  
  import java.io.IOException;
  import java.net.UnknownHostException;
  
  import org.bson.types.ObjectId;
  
  import com.mongodb.BasicDBList;
  import com.mongodb.BasicDBObject;
  import com.mongodb.DB;
  import com.mongodb.DBCollection;
  import com.mongodb.DBCursor;
  
  public class Country {
      public BasicDBObject addDemo(long _id ) throws IOException {
          DB db=ConnectToDB.getConnection();
  
          DBCollection collection = db.getCollection("demo");
           BasicDBObject buildList = null;
              BasicDBObject document = new BasicDBObject();
              document.put("_id",new ObjectId("id"));
              collection.save(document);
              return buildList;
      }
  
  }
  
  
  //getResponse.java
  
  package com.speed.infoaxon;
  
  import java.io.IOException;
  import java.net.UnknownHostException;
  
  import javax.ws.rs.Consumes;
  import javax.ws.rs.FormParam;
  import javax.ws.rs.POST;
  import javax.ws.rs.Path;
  import javax.ws.rs.Produces;
  import javax.ws.rs.core.MediaType;
  
  import com.mongodb.BasicDBList;
  import com.mongodb.BasicDBObject;
  
  @Path("/add")
  public class GetResponse {
  
      @POST
      @Path("/addDemo")
      @Consumes({MediaType.APPLICATION_JSON, MediaType.APPLICATION_FORM_URLENCODED} )
  
      public BasicDBObject addDemo(@FormParam("_id") long _id) throws IOException
      { 
          System.out.println("inside demo");
         Country d = new Country();
          BasicDBObject basicDBList=d.addDemo(_id);
  
          return basicDBList;
  
      }
  }
  
  Please let me know where is the issue. Thanks in advance.
  </code></pre>