String sql = "something";
String query = "something";
List a = Arrays.asList("Context-Type", "Application/x-www-form-urlencoded");
List b = Arrays.asList(a);
Web web = new Web();
web.Url("your url");
web.RequestHeaders(YailList.makeList(b));
List key = Arrays.asList("key", web.UriEncode(sql));
List queryy = Arrays.asList("query", web.UriEncode(query));
List requestData = Arrays.asList(key, queryy);
web.PostText(web.BuildRequestData(requestData));
you have to import -
com.google.appinventor.components.runtime.Web;
java.util.List;
java.util.Arrays;