diff --git a/partial-response/src/main/java/com/iluwatar/partialresponse/FieldJsonMapper.java b/partial-response/src/main/java/com/iluwatar/partialresponse/FieldJsonMapper.java
index 32e9ae83d..dce164f0d 100644
--- a/partial-response/src/main/java/com/iluwatar/partialresponse/FieldJsonMapper.java
+++ b/partial-response/src/main/java/com/iluwatar/partialresponse/FieldJsonMapper.java
@@ -24,7 +24,16 @@
 
 package com.iluwatar.partialresponse;
 
+/**
+ * Map a video to json
+ */
 public class FieldJsonMapper {
+
+  /**
+   * @param video  object containing video information
+   * @param fields fields information to get
+   * @return json of required fields from video
+   */
   public String toJson(Video video, String[] fields) {
     return null;
   }
diff --git a/partial-response/src/main/java/com/iluwatar/partialresponse/Video.java b/partial-response/src/main/java/com/iluwatar/partialresponse/Video.java
index d8d80fd00..7310f26b0 100644
--- a/partial-response/src/main/java/com/iluwatar/partialresponse/Video.java
+++ b/partial-response/src/main/java/com/iluwatar/partialresponse/Video.java
@@ -53,15 +53,18 @@ public class Video {
     this.language = language;
   }
 
+  /**
+   * @return json representaion of video
+   */
   @Override
   public String toString() {
-    return "{" +
-        "\"id\": \"" + id + "\"," +
-        "\"title\": \"" + title + "\"," +
-        "\"length\": " + length + "," +
-        "\"description\": \"" + description + "\"," +
-        "\"director\": \"" + director + "\"," +
-        "\"language\": \"" + language + "\"," +
-        "}";
+    return "{"
+        + "\"id\": \"" + id + "\","
+        + "\"title\": \"" + title + "\","
+        + "\"length\": " + length + ","
+        + "\"description\": \"" + description + "\","
+        + "\"director\": \"" + director + "\","
+        + "\"language\": \"" + language + "\","
+        + "}";
   }
 }
diff --git a/partial-response/src/main/java/com/iluwatar/partialresponse/VideoResource.java b/partial-response/src/main/java/com/iluwatar/partialresponse/VideoResource.java
index 8c571e6d6..457ecec00 100644
--- a/partial-response/src/main/java/com/iluwatar/partialresponse/VideoResource.java
+++ b/partial-response/src/main/java/com/iluwatar/partialresponse/VideoResource.java
@@ -26,15 +26,28 @@ package com.iluwatar.partialresponse;
 
 import java.util.Map;
 
+/**
+ * The resource class which serves video information.
+ * This class act as server in the demo. Which has all video details.
+ */
 public class VideoResource {
   private FieldJsonMapper fieldJsonMapper;
   private Map<Integer, Video> videos;
 
+  /**
+   * @param fieldJsonMapper map object to json.
+   * @param videos          initialize resource with existing videos. Act as database.
+   */
   public VideoResource(FieldJsonMapper fieldJsonMapper, Map<Integer, Video> videos) {
     this.fieldJsonMapper = fieldJsonMapper;
     this.videos = videos;
   }
 
+  /**
+   * @param id     video id
+   * @param fields fields to get information about
+   * @return json of specified fields of particular video by id
+   */
   public String getDetails(Integer id, String... fields) {
     if (fields.length == 0) {
       return videos.get(id).toString();
diff --git a/partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java b/partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java
index df25c2dea..d420863a8 100644
--- a/partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java
+++ b/partial-response/src/test/java/com/iluwatar/partialresponse/VideoResourceTest.java
@@ -38,6 +38,9 @@ import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.when;
 
+/**
+ * tests {@link VideoResource}.
+ */
 @RunWith(MockitoJUnitRunner.class)
 public class VideoResourceTest {
   @Mock
@@ -58,7 +61,8 @@ public class VideoResourceTest {
   public void shouldGiveVideoDetailsById() {
     String actualDetails = resource.getDetails(1);
 
-    String expectedDetails = "{\"id\": \"1\",\"title\": \"Avatar\",\"length\": 178,\"description\": \"epic science fiction film\",\"director\": \"James Cameron\",\"language\": \"English\",}";
+    String expectedDetails = "{\"id\": \"1\",\"title\": \"Avatar\",\"length\": 178,\"description\": "
+        + "\"epic science fiction film\",\"director\": \"James Cameron\",\"language\": \"English\",}";
     assertEquals(expectedDetails, actualDetails);
   }