Changeset 1303

Timestamp:

12.03.2012 14:28:58 (15 months ago)

Author:

raido

Message:

StringBuilder? fix

Files:

• backoffice/trunk/src/main/java/ee/tlu/htk/dippler/managers/ListingManager.java (modified) (39 diffs)

backoffice/trunk/src/main/java/ee/tlu/htk/dippler/managers/ListingManager.java

@@ -293 +293 @@
 
     public String listCourses(Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Course c WHERE c.approved", Course.class);
@@ -300 +300 @@
             List<Course> courses = (List<Course>) listing.getResultList();
             for(Course course : courses ){
-                xml = xml + "<id>"+course.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(course.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listEnrolledCourses(User user, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Learner l WHERE l.learner=?1", Learner.class);
@@ -317 +317 @@
             List<Learner> learners = (List<Learner>) listing.getResultList();
             for(Learner learner : learners ){
-                xml = xml + "<id>"+learner.getCourse().getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(learner.getCourse().getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listEnrollableCourses(User user, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Course c WHERE c.approved AND c.enrollment<3 AND (SELECT count(course) FROM Learner l WHERE l.learner=?1 AND l.course=c.id)<1", Course.class);
@@ -334 +334 @@
             List<Course> courses = (List<Course>) listing.getResultList();
             for(Course course : courses ){
-                xml = xml + "<id>"+course.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(course.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listOrganizationCourses(Long org_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Course c WHERE c.approved AND c.organization=?1", Course.class);
@@ -351 +351 @@
             List<Course> courses = (List<Course>) listing.getResultList();
             for(Course course : courses ){
-                xml = xml + "<id>"+course.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(course.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listMyOrganizationCourses(Long org_id, Integer offset, Integer limit, User user) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Course c WHERE c.owner=?1 AND c.organization=?2", Course.class);
@@ -369 +369 @@
             List<Course> courses = (List<Course>) listing.getResultList();
             for(Course course : courses ){
-                xml = xml + "<id>"+course.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(course.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listUnapprovedOrganizationCourses(Long org_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Course c WHERE !c.approved AND c.organization=?1", Course.class);
@@ -386 +386 @@
             List<Course> courses = (List<Course>) listing.getResultList();
             for(Course course : courses ){
-                xml = xml + "<id>"+course.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(course.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listLearners(Long course_id, Integer status) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Learner l WHERE l.status>=?1 AND l.course=?2", Learner.class);
@@ -402 +402 @@
             List<Learner> learners = (List<Learner>) listing.getResultList();
             for(Learner learner : learners ){
-                xml = xml + "<id>"+learner.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(learner.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
@@ -422 +422 @@
             List<Assignment> assignments = (List<Assignment>) listing.getResultList();
             for(Assignment assignment : assignments ){
-                xml.append("<id>"+assignment.getId()+"</id>");
+                xml.append("<id>").append(assignment.getId()).append("</id>");
             }
         } catch (Exception e) {
@@ -431 +431 @@
 
     public String listAssignmentsFull(Long course_id, Integer offset, Integer limit) {
-        String xml = "<assignments>";
+        StringBuilder xml = new StringBuilder("<assignments>");
         try {
             Query find_course = em.createNamedQuery("Course.findById");
@@ -443 +443 @@
             for(Assignment assignment : assignments ){
                 try {
-                    xml += assignmentManager.marshal(assignment);
+                    xml.append(assignmentManager.marshal(assignment));
                 } catch (Throwable ex) {
                     Logger.getLogger(ListingManager.class.getName()).log(Level.SEVERE, null, ex);
@@ -451 +451 @@
 
         }
-        xml += "</assignments>";
-        return xml;
+        xml.append("</assignments>");
+        return xml.toString();
     }
 
     public String listAnswers(Long assignment_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query find_assignment = em.createNamedQuery("Assignment.findById");
@@ -467 +467 @@
             List<Answer> answers = (List<Answer>) listing.getResultList();
             for(Answer answer : answers ){
-                xml = xml + "<id>"+answer.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(answer.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listGroups(Long course_id, Integer offset, Integer limit, String sorter) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         ArrayList<String> sorter_al = Sorter.parseSorted(sorter, "coursegroup");
         try {
@@ -497 +497 @@
             List<Coursegroup> groups = (List<Coursegroup>) listing.getResultList();
             for(Coursegroup group : groups ){
-                xml = xml + "<id>"+group.getId()+"</id>";
+                xml.append("<id>").append(group.getId()).append("</id>");
             }
         } catch (Exception e) {
             e.printStackTrace(System.err);
         }
-        return xml;
+        return xml.toString();
     }
 
     public String listGroupMembers(Long group_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query find = em.createNamedQuery("Coursegroup.findById");
@@ -513 +513 @@
             Collection<Learner> members = group.getMembers();
             for(Learner member : members ){
-                xml = xml + "<id>"+member.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(member.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listCourseblogPosts(Long course, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Courseblog_Post c WHERE c.course=?1 AND !c.hidden ORDER BY c.created DESC", CourseblogPost.class);
@@ -530 +530 @@
             List<CourseblogPost> posts = (List<CourseblogPost>) listing.getResultList();
             for(CourseblogPost post : posts ){
-                xml = xml + "<id>"+post.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(post.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listCourseblogComments(Long post, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Courseblog_Comment c WHERE c.courseblog_post=?1 AND !c.hidden", CourseblogComment.class);
@@ -547 +547 @@
             List<CourseblogComment> comments = (List<CourseblogComment>) listing.getResultList();
             for(CourseblogComment comment : comments ){
-                xml = xml + "<id>"+comment.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                 xml.append("<id>").append(comment.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listCourseComments(Long course_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Courseblog_Comment c WHERE c.course=?1 AND !c.hidden", CourseblogComment.class);
@@ -564 +564 @@
             List<CourseblogComment> comments = (List<CourseblogComment>) listing.getResultList();
             for(CourseblogComment comment : comments ){
-                xml = xml + "<id>"+comment.getId()+"</id>";
+                 xml.append("<id>").append(comment.getId()).append("</id>");
             }
         } catch (Exception e) {
             
         }
-        return xml;
+        return xml.toString();
     }
 
     public String listTags(Long parent_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM tag t", Tag.class);
@@ -581 +581 @@
             List<Tag> tags = (List<Tag>) listing.getResultList();
             for(Tag tag : tags ){
-                xml = xml + "<id>"+tag.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(tag.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listCategories(Long parent_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM category c WHERE c.parent=?1", Category.class);
@@ -598 +598 @@
             List<Category> categories = (List<Category>) listing.getResultList();
             for(Category cat : categories ){
-                xml = xml + "<id>"+cat.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(cat.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
     
     public String listNotApprovedUsers(Long org, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM User u LEFT JOIN user_organization uo ON u.id=uo.user WHERE !u.approved AND uo.organization=?1", User.class);
@@ -615 +615 @@
             List<User> users = (List<User>) listing.getResultList();
             for(User user : users ){
-                xml = xml + "<id>"+user.getId()+"</id>";
+                xml.append("<id>").append(user.getId()).append("</id>");
             }
         } catch (Exception e) {
             
         }
-        return xml;
+        return xml.toString();
     }
 
     public String listApprovedUsers(Long org, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM User u LEFT JOIN user_organization uo ON u.id=uo.user WHERE u.approved AND uo.organization=?1", User.class);
@@ -632 +632 @@
             List<User> users = (List<User>) listing.getResultList();
             for(User user : users ){
-                xml = xml + "<id>"+user.getId()+"</id>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<id>").append(user.getId()).append("</id>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
     
     public String listComboboxResourceFolders(Long course_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query folderListing = em.createNativeQuery("SELECT * FROM resource_folder f WHERE f.course=?1 AND f.parent IS NULL ORDER BY f.position ASC", ResourceFolder.class);
@@ -650 +650 @@
             List<ResourceFolder> folders = (List<ResourceFolder>) folderListing.getResultList();
             // TODO list according to weight
-            xml = xml + "<foldertree>";
+            xml.append("<foldertree>");
             for(ResourceFolder folder : folders){
-                xml = xml + "<folder>";
-                xml = xml + "<id>"+folder.getId()+"</id>";
-                xml = xml + "<title>"+folder.getTitle()+"</title>";
+                xml.append("<folder>");
+                xml.append("<id>").append(folder.getId()).append("</id>");
+                xml.append("<title>").append(folder.getTitle()).append("</title>");
                 // xml = xml + "<description>"+folder.getDescription()+"</description>";
-                xml = xml + listSubfolders(folder.getId(), offset, limit);
-                xml = xml + "</folder>";
-            }
-            xml = xml + "</foldertree>";
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append(listSubfolders(folder.getId(), offset, limit));
+                xml.append("</folder>");
+            }
+            xml.append("</foldertree>");
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
     
     public String listSubfolders(Long folder_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM resource_folder f WHERE f.parent=?1 ORDER BY f.position ASC", ResourceFolder.class);
@@ -674 +674 @@
             listing.setMaxResults(limit);
             if(listing.getResultList().isEmpty()) {
-                return xml;
+                return "";
             }
             List<ResourceFolder> folders = (List<ResourceFolder>) listing.getResultList();
-            xml = xml + "<folders>";
+            xml.append("<folders>");
             for(ResourceFolder folder : folders){
-                xml = xml + "<folder>";
-                xml = xml + "<id>"+folder.getId()+"</id>";
-                xml = xml + "<title>"+folder.getTitle()+"</title>";
-                xml = xml + listSubfolders(folder.getId(), offset, limit);
-                xml = xml + "</folder>";
-            }
-        xml = xml + "</folders>";
-        } catch (Exception e) {
-
-        }
-        return xml;
+                xml.append("<folder>");
+                xml.append("<id>").append(folder.getId()).append("</id>");
+                xml.append("<title>").append(folder.getTitle()).append("</title>");
+                // xml = xml + "<description>"+folder.getDescription()+"</description>";
+                xml.append(listSubfolders(folder.getId(), offset, limit));
+                xml.append("</folder>");
+            }
+        xml.append("</folders>");
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
         
         // TODO EMPTY QUERY CHECKS
     public String listResourceFolders(Long course_id, Integer offset, Integer limit) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM resource_folder f WHERE f.course=?1 AND f.parent IS NULL ORDER BY f.position ASC", ResourceFolder.class);
@@ -702 +703 @@
             if(listing.getResultList().isEmpty()) {
                 // return resources/folders with appropriate course_id?
-                return xml;
+                return xml.toString();
             }
             List<ResourceFolder> folders = (List<ResourceFolder>) listing.getResultList();
             for(ResourceFolder folder : folders){
-                xml = xml + "<folder>";
-                xml = xml + "<id>"+folder.getId()+"</id>";
-                xml = xml + "<title>"+folder.getTitle()+"</title>";
+                xml.append("<folder>");
+                xml.append("<id>").append(folder.getId()).append("</id>");
+                xml.append("<title>").append(folder.getTitle()).append("</title>");
                 // SUBFOLDERS
                 Query sublisting = em.createNativeQuery("SELECT * FROM resource_folder f WHERE f.parent=?1 ORDER BY f.position ASC", ResourceFolder.class);
@@ -715 +716 @@
                 sublisting.setMaxResults(limit);
                 List<ResourceFolder> subfolders = (List<ResourceFolder>) sublisting.getResultList();
-                xml = xml + "<folders>";
+                xml.append("<folders>");
                 for(ResourceFolder subfolder : subfolders){
-                    xml = xml + "<folder>";
-                    xml = xml + "<id>"+subfolder.getId()+"</id>";
-                    xml = xml + "<title>"+subfolder.getTitle()+"</title>";
-                    xml = xml + "</folder>";
-                }
-                xml = xml + "</folders>";
+                    xml.append("<folder>");
+                    xml.append("<id>").append(subfolder.getId()).append("</id>");
+                    xml.append("<title>").append(subfolder.getTitle()).append("</title>");
+                    xml.append("</folder>");
+                }
+                xml.append("</folders>");
  
                 Query resourceListing = em.createNativeQuery("SELECT * FROM learning_resource r WHERE r.folder=?1 ORDER BY f.position ASC", LearningResource.class);
@@ -731 +732 @@
                 List<LearningResource> resources = (List<LearningResource>) resourceListing.getResultList();
                 for(LearningResource resource : resources){
-                    xml = xml + "<resource>";
-                    xml = xml + "<id>"+resource.getId()+"</id>";
-                    xml = xml + "<title>"+resource.getTitle()+"</title>";
-                    xml = xml + "<description>"+resource.getDescription()+"</description>";
-                    xml = xml + "<type>"+resource.getType()+"</type>";
-                    xml = xml + "<author>"+resource.getAuthor()+"</author>";
-                    xml = xml + "<published>"+resource.getPublished()+"</published>";
+                    xml.append("<resource>");
+                    xml.append("<id>").append(resource.getId()).append("</id>");
+                    xml.append("<title>").append(resource.getTitle()).append("</title>");
+                    xml.append("<description>").append(resource.getDescription()).append("</description>");
+                    xml.append("<type>").append(resource.getType()).append("</type>");
+                    xml.append("<author>").append(resource.getAuthor()).append("</author>");
+                    xml.append("<published>").append(resource.getPublished()).append("</published>");
                     // add author?
-                    xml = xml + "</resource>";
-                }
-                xml = xml + "</folder>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                    xml.append("</resource>");
+                }
+                xml.append("</folder>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
@@ -776 +777 @@
     
     public String listLearnersFull(Long course_id, Integer status) {
-        String xml = "<learners>";
+        StringBuilder xml = new StringBuilder("<learners>");
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Learner l WHERE l.status>=?1 AND l.course=?2", Learner.class);
@@ -784 +785 @@
             for(Learner learner : learners ) {
                 try {
-                    xml += learnerManager.marshal(learner);
+                    xml.append(learnerManager.marshal(learner));
                 } catch (Throwable t) {
                     
@@ -792 +793 @@
 
         }
-        xml += "</learners>";
-        return xml;
+        xml.append("</learners>");
+        return xml.toString();
     }
 
     public String listFacilitatorsFull(Long course_id, Integer status) {
-        String xml = "<facilitators>";
+        StringBuilder xml = new StringBuilder("<facilitators>");
         try {
             Query listing = em.createNativeQuery("SELECT * FROM Facilitator l WHERE l.status>=?1 AND l.course=?2", Facilitator.class);
@@ -805 +806 @@
             for(Facilitator facilitator : facilitators ) {
                 try {
-                    xml += facilitatorManager.marshal(facilitator);
+                    xml.append(facilitatorManager.marshal(facilitator));
                 } catch (Throwable t) {
 
@@ -813 +814 @@
 
         }
-        xml += "</facilitators>";
-        return xml;
+        xml.append("</facilitators>");
+        return xml.toString();
     }
 
     public String listOutcomesFull(Long course_id) {
-        String xml = "<learningoutcomes>";
+        StringBuilder xml = new StringBuilder("<learningoutcomes>");
         try {
             Query listing = em.createNativeQuery("SELECT * FROM learning_outcome l WHERE l.course=?1", LearningOutcome.class);
@@ -825 +826 @@
             for(LearningOutcome outcome : outcomes ) {
                 try {
-                    xml += outcomeManager.marshal(outcome);
+                    xml.append(outcomeManager.marshal(outcome));
                 } catch (Throwable t) {
 
@@ -833 +834 @@
 
         }
-        xml += "</learningoutcomes>";
-        return xml;
+        xml.append("</learningoutcomes>");
+        return xml.toString();
     }
 
     public String listCategoriesFull(Long course_id) {
-        String xml = "<categories>";
+        StringBuilder xml = new StringBuilder("<categories>");
         try {
             Query listing = em.createNativeQuery("SELECT * FROM category c WHERE c.course=?1", Category.class);
@@ -848 +849 @@
                     parent = category.getParentCategory().getId().toString();
                 } catch (Exception e) {}
-                xml += "<category>"+
-                       "<id>"+category.getId()+"</id>"+
-                       "<name><![CDATA["+category.getName()+"]]></name>"+
-                       "<slug><![CDATA["+category.getSlug()+"]]></slug>"+
-                       "<count>"+category.getCount()+"</count>"+
-                       "<parent>"+parent+"</parent>"+
-                       "<course>"+category.getCourse().getId().toString()+"</course>"+
-                       "<categories></categories>"+
-                       "</category>";
-            }
-        } catch (Exception e) {
-
-        }
-        xml += "</categories>";
-        return xml;
+                xml.append("<category>");
+                       xml.append("<id>").append(category.getId()).append("</id>");
+                       xml.append("<name><![CDATA[").append(category.getName()).append("]]></name>");
+                       xml.append("<slug><![CDATA[").append(category.getSlug()).append("]]></slug>");
+                       xml.append("<count>").append(category.getCount()).append("</count>");
+                       xml.append("<parent>").append(parent).append("</parent>");
+                       xml.append("<course>").append(category.getCourse().getId().toString()).append("</course>");
+                       xml.append("<categories></categories>");
+                       xml.append("</category>");
+            }
+        } catch (Exception e) {
+
+        }
+        xml.append("</categories>");
+        return xml.toString();
     }
 
     public String listCategoriesTreeFull(Long course_id) {
-        String xml = "<categories>";
+        StringBuilder xml = new StringBuilder("<categories>");
         try {
             Query listing = em.createNativeQuery("SELECT * FROM category c WHERE c.course=?1 AND c.parent is NULL ORDER BY c.name ASC", Category.class);
@@ -872 +873 @@
             List<Category> categories = (List<Category>) listing.getResultList();
             for(Category category : categories ) {
-                xml += "<category>"+
-                       "<id>"+category.getId()+"</id>"+
-                       "<name><![CDATA["+category.getName()+"]]></name>"+
-                       "<slug><![CDATA["+category.getSlug()+"]]></slug>"+
-                       "<count>"+category.getCount()+"</count>"+
-                       "<parent></parent>"+
-                       "<course>"+category.getCourse().getId().toString()+"</course>"+
-                       "<categories>"+listSubCategoriesTreeFull(course_id, category)+"</categories>"+
-                       "</category>";
-            }
-        } catch (Exception e) {
-
-        }
-        xml += "</categories>";
-        return xml;
+                xml.append("<category>");
+                       xml.append("<id>").append(category.getId()).append("</id>");
+                       xml.append("<name><![CDATA[").append(category.getName()).append("]]></name>");
+                       xml.append("<slug><![CDATA[").append(category.getSlug()).append("]]></slug>");
+                       xml.append("<count>").append(category.getCount()).append("</count>");
+                       xml.append("<parent></parent>");
+                       xml.append("<course>").append(category.getCourse().getId().toString()).append("</course>");
+                       xml.append("<categories>").append(listSubCategoriesTreeFull(course_id, category)).append("</categories>");
+                       xml.append("</category>");
+            }
+        } catch (Exception e) {
+
+        }
+        xml.append("</categories>");
+        return xml.toString();
     }
 
     public String listSubCategoriesTreeFull(Long course_id, Category cat) {
-        String xml = "";
+        StringBuilder xml = new StringBuilder();
         try {
             Query listing = em.createNativeQuery("SELECT * FROM category c WHERE c.course=?1 AND c.parent=?2 ORDER BY c.name ASC", Category.class);
@@ -901 +902 @@
                     parent = category.getParentCategory().getId().toString();
                 } catch (Exception e) {}
-                xml += "<category>"+
-                       "<id>"+category.getId()+"</id>"+
-                       "<name><![CDATA["+category.getName()+"]]></name>"+
-                       "<slug><![CDATA["+category.getSlug()+"]]></slug>"+
-                       "<count>"+category.getCount()+"</count>"+
-                       "<parent>"+parent+"</parent>"+
-                       "<course>"+category.getCourse().getId().toString()+"</course>"+
-                       "<categories>"+listSubCategoriesTreeFull(course_id, category)+"</categories>"+
-                       "</category>";
-            }
-        } catch (Exception e) {
-
-        }
-        return xml;
+                    xml.append("<category>");
+                       xml.append("<id>").append(category.getId()).append("</id>");
+                       xml.append("<name><![CDATA[").append(category.getName()).append("]]></name>");
+                       xml.append("<slug><![CDATA[").append(category.getSlug()).append("]]></slug>");
+                       xml.append("<count>").append(category.getCount()).append("</count>");
+                       xml.append("<parent>").append(parent).append("</parent>");
+                       xml.append("<course>").append(category.getCourse().getId().toString()).append("</course>");
+                       xml.append("<categories>").append(listSubCategoriesTreeFull(course_id, category)).append("</categories>");
+                       xml.append("</category>");
+            }
+        } catch (Exception e) {
+
+        }
+        return xml.toString();
     }
 
     public String listActivities(User user, Long course_id, Integer offset, Integer limit) {
-        String xml = "<activities>";
+        StringBuilder xml = new StringBuilder("<activities>");
         try {
             Course course = courseManager.findById(course_id);
@@ -946 +947 @@
                 List<Activity> activities = (List<Activity>) listing.getResultList();
                 for (Activity activity : activities) {
-                    xml += activityManager.marshal(activity);
+                    xml.append(activityManager.marshal(activity));
                 }
             }
@@ -952 +953 @@
             t.printStackTrace(System.out);
         }
-        xml += "</activities>";
-        return xml;
+        xml.append("</activities>");
+        return xml.toString();
     }