Fix last errors in checkstyle.

caching/src/main/java/com/iluwatar/caching/CachingPolicy.java

@@ -32,10 +32,25 @@ import lombok.Getter;
 @AllArgsConstructor
 @Getter
 public enum CachingPolicy {
+  /**
+   * Through.
+   */
   THROUGH("through"),
+  /**
+   * AROUND.
+   */
   AROUND("around"),
+  /**
+   * BEHIND.
+   */
   BEHIND("behind"),
+  /**
+   * ASIDE.
+   */
   ASIDE("aside");
 
+  /**
+   * Policy value.
+   */
   private final String policy;
 }

caching/src/main/java/com/iluwatar/caching/LruCache.java

@@ -30,40 +30,78 @@ import java.util.Map;
 import lombok.extern.slf4j.Slf4j;
 
 /**
- * Data structure/implementation of the application's cache. The data structure consists of a hash
+ * Data structure/implementation of the application's cache. The data structure
- * table attached with a doubly linked-list. The linked-list helps in capturing and maintaining the
+ * consists of a hash table attached with a doubly linked-list. The linked-list
- * LRU data in the cache. When a data is queried (from the cache), added (to the cache), or updated,
+ * helps in capturing and maintaining the LRU data in the cache. When a data is
- * the data is moved to the front of the list to depict itself as the most-recently-used data. The
+ * queried (from the cache), added (to the cache), or updated, the data is
- * LRU data is always at the end of the list.
+ * moved to the front of the list to depict itself as the most-recently-used
+ * data. The LRU data is always at the end of the list.
  */
 @Slf4j
 public class LruCache {
-
+  /**
+   * Static class Node.
+   */
   static class Node {
-    String userId;
+    /**
-    UserAccount userAccount;
+     * user id.
-    Node previous;
+     */
-    Node next;
+    private final String userId;
+    /**
+     * User Account.
+     */
+    private UserAccount userAccount;
+    /**
+     * previous.
+     */
+    private Node previous;
+    /**
+     * next.
+     */
+    private Node next;
 
-    public Node(String userId, UserAccount userAccount) {
+    /**
-      this.userId = userId;
+     * Node definition.
-      this.userAccount = userAccount;
+     * @param id String
+     * @param account {@link UserAccount}
+     */
+    Node(final String id, final UserAccount account) {
+      this.userId = id;
+      this.userAccount = account;
     }
   }
 
-  int capacity;
+  /**
-  Map<String, Node> cache = new HashMap<>();
+   * Capacity of Cache.
-  Node head;
+   */
-  Node end;
+  private int capacity;
+  /**
+   * Cache {@link HashMap}.
+   */
+  private Map<String, Node> cache = new HashMap<>();
+  /**
+   * Head.
+   */
+  private Node head;
+  /**
+   * End.
+   */
+  private Node end;
 
-  public LruCache(int capacity) {
+  /**
-    this.capacity = capacity;
+   * Constructor.
+   * @param cap Integer.
+   */
+  public LruCache(final int cap) {
+    this.capacity = cap;
   }
 
   /**
    * Get user account.
+   * @param userId String
+   * @return {@link UserAccount}
    */
-  public UserAccount get(String userId) {
+  public UserAccount get(final String userId) {
     if (cache.containsKey(userId)) {
       var node = cache.get(userId);
       remove(node);
@@ -75,8 +113,9 @@ public class LruCache {
 
   /**
    * Remove node from linked list.
+   * @param node {@link Node}
    */
-  public void remove(Node node) {
+  public void remove(final Node node) {
     if (node.previous != null) {
       node.previous.next = node.next;
     } else {
@@ -91,8 +130,9 @@ public class LruCache {
 
   /**
    * Move node to the front of the list.
+   * @param node {@link Node}
    */
-  public void setHead(Node node) {
+  public void setHead(final Node node) {
     node.next = head;
     node.previous = null;
     if (head != null) {
@@ -106,8 +146,10 @@ public class LruCache {
 
   /**
    * Set user account.
+   * @param userAccount {@link UserAccount}
+   * @param userId {@link String}
    */
-  public void set(String userId, UserAccount userAccount) {
+  public void set(final String userId, final UserAccount userAccount) {
     if (cache.containsKey(userId)) {
       var old = cache.get(userId);
       old.userAccount = userAccount;
@@ -127,25 +169,40 @@ public class LruCache {
     }
   }
 
-  public boolean contains(String userId) {
+    /**
+     * Che if Cache cintains the userId.
+     * @param userId {@link String}
+     * @return boolean
+     */
+  public boolean contains(final String userId) {
     return cache.containsKey(userId);
   }
 
     /**
      *  Invalidate cache for user.
+     * @param userId {@link String}
      */
-  public void invalidate(String userId) {
+  public void invalidate(final String userId) {
     var toBeRemoved = cache.remove(userId);
     if (toBeRemoved != null) {
-      LOGGER.info("# {} has been updated! Removing older version from cache...", userId);
+      LOGGER.info("# {} has been updated! "
+              + "Removing older version from cache...", userId);
       remove(toBeRemoved);
     }
   }
 
+    /**
+     * Is cache full?
+     * @return boolean
+     */
   public boolean isFull() {
     return cache.size() >= capacity;
   }
 
+    /**
+     * Get LRU data.
+     * @return {@link UserAccount}
+     */
   public UserAccount getLruData() {
     return end.userAccount;
   }
@@ -161,6 +218,7 @@ public class LruCache {
 
   /**
    * Returns cache data in list form.
+   * @return {@link List}
    */
   public List<UserAccount> getCacheDataInListForm() {
     var listOfCacheData = new ArrayList<UserAccount>();
@@ -174,10 +232,13 @@ public class LruCache {
 
   /**
    * Set cache capacity.
+   * @param newCapacity int
    */
-  public void setCapacity(int newCapacity) {
+  public void setCapacity(final int newCapacity) {
     if (capacity > newCapacity) {
-      clear(); // Behavior can be modified to accommodate for decrease in cache size. For now, we'll
+      // Behavior can be modified to accommodate
+      // for decrease in cache size. For now, we'll
+      clear();
       // just clear the cache.
     } else {
       this.capacity = newCapacity;

caching/src/main/java/com/iluwatar/caching/UserAccount.java

@@ -36,7 +36,16 @@ import lombok.ToString;
 @AllArgsConstructor
 @ToString
 public class UserAccount {
+  /**
+   * User Id.
+   */
   private String userId;
+  /**
+   * User Name.
+   */
   private String userName;
+  /**
+   * Additional Info.
+   */
   private String additionalInfo;
 }

caching/src/main/java/com/iluwatar/caching/constants/CachingConstants.java

@@ -26,11 +26,27 @@ package com.iluwatar.caching.constants;
 /**
  * Constant class for defining constants.
  */
-public class CachingConstants {
+public final class CachingConstants {
-
+  /**
+   * User Account.
+   */
   public static final String USER_ACCOUNT = "user_accounts";
+  /**
+   * User ID.
+   */
   public static final String USER_ID = "userID";
+  /**
+   * User Name.
+   */
   public static final String USER_NAME = "userName";
+  /**
+   * Additional Info.
+   */
   public static final String ADD_INFO = "additionalInfo";
 
+  /**
+   * Constructor.
+   */
+  private CachingConstants() {
+  }
 }

caching/src/main/java/com/iluwatar/caching/constants/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Constants.
+ */
+package com.iluwatar.caching.constants;

caching/src/main/java/com/iluwatar/caching/database/DbManagerFactory.java

@@ -1,8 +1,23 @@
 package com.iluwatar.caching.database;
 
-public class DbManagerFactory {
+/**
-    public static DbManager initDb(boolean isMongo){
+ * Creates the database connection accroding the input parameter.
-        if(isMongo){
+ */
+public final class DbManagerFactory {
+    /**
+     * Private constructor.
+     */
+    private DbManagerFactory() {
+    }
+
+    /**
+     * Init database.
+     *
+     * @param isMongo boolean
+     * @return {@link DbManager}
+     */
+    public static DbManager initDb(final boolean isMongo) {
+        if (isMongo) {
             return new MongoDb();
         }
         return new VirtualDb();

caching/src/main/java/com/iluwatar/caching/database/MongoDb.java

@@ -7,72 +7,111 @@ import com.mongodb.client.MongoDatabase;
 import com.mongodb.client.model.UpdateOptions;
 import org.bson.Document;
 
+import static com.iluwatar.caching.constants.CachingConstants.USER_NAME;
+import static com.iluwatar.caching.constants.CachingConstants.ADD_INFO;
+import static com.iluwatar.caching.constants.CachingConstants.USER_ID;
+import static com.iluwatar.caching.constants.CachingConstants.USER_ACCOUNT;
+
 /**
  * Implementation of DatabaseManager.
  * implements base methods to work with MongoDb.
  */
 public class MongoDb implements DbManager {
+    /**
+     * Mongo db.
+     */
     private MongoDatabase db;
 
+    /**
+     * Connect to Db.
+     */
     @Override
     public void connect() {
         MongoClient mongoClient = new MongoClient();
         db = mongoClient.getDatabase("test");
     }
 
+    /**
+     * Read data from DB.
+     *
+     * @param userId {@link String}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount readFromDb(String userId) {
+    public UserAccount readFromDb(final String userId) {
         if (db == null) {
             connect();
         }
         var iterable = db
                 .getCollection(CachingConstants.USER_ACCOUNT)
-                .find(new Document(CachingConstants.USER_ID, userId));
+                .find(new Document(USER_ID, userId));
         if (iterable == null) {
             return null;
         }
         Document doc = iterable.first();
-        String userName = doc.getString(CachingConstants.USER_NAME);
+        String userName = doc.getString(USER_NAME);
-        String appInfo = doc.getString(CachingConstants.ADD_INFO);
+        String appInfo = doc.getString(ADD_INFO);
         return new UserAccount(userId, userName, appInfo);
     }
 
+    /**
+     * Write data to DB.
+     *
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount writeToDb(UserAccount userAccount) {
+    public UserAccount writeToDb(final UserAccount userAccount) {
         if (db == null) {
             connect();
         }
-        db.getCollection(CachingConstants.USER_ACCOUNT).insertOne(
+        db.getCollection(USER_ACCOUNT).insertOne(
-                new Document(CachingConstants.USER_ID, userAccount.getUserId())
+                new Document(USER_ID, userAccount.getUserId())
-                        .append(CachingConstants.USER_NAME, userAccount.getUserName())
+                        .append(USER_NAME, userAccount.getUserName())
-                        .append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
+                        .append(ADD_INFO, userAccount.getAdditionalInfo())
         );
         return userAccount;
     }
 
+    /**
+     * Update DB.
+     *
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount updateDb(UserAccount userAccount) {
+    public UserAccount updateDb(final UserAccount userAccount) {
         if (db == null) {
             connect();
         }
-        db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
+        Document id = new Document(USER_ID, userAccount.getUserId());
-                new Document(CachingConstants.USER_ID, userAccount.getUserId()),
+        Document dataSet = new Document(USER_NAME, userAccount.getUserName())
-                new Document("$set", new Document(CachingConstants.USER_NAME, userAccount.getUserName())
+                .append(ADD_INFO, userAccount.getAdditionalInfo());
-                        .append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())));
+        db.getCollection(CachingConstants.USER_ACCOUNT)
+                .updateOne(id, new Document("$set", dataSet));
         return userAccount;
     }
 
+    /**
+     * Update data if exists.
+     *
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount upsertDb(UserAccount userAccount) {
+    public UserAccount upsertDb(final UserAccount userAccount) {
         if (db == null) {
             connect();
         }
+        String userId = userAccount.getUserId();
+        String userName = userAccount.getUserName();
+        String additionalInfo = userAccount.getAdditionalInfo();
         db.getCollection(CachingConstants.USER_ACCOUNT).updateOne(
-                new Document(CachingConstants.USER_ID, userAccount.getUserId()),
+                new Document(USER_ID, userId),
                 new Document("$set",
-                        new Document(CachingConstants.USER_ID, userAccount.getUserId())
+                        new Document(USER_ID, userId)
-                                .append(CachingConstants.USER_NAME, userAccount.getUserName())
+                                .append(USER_NAME, userName)
-                                .append(CachingConstants.ADD_INFO, userAccount.getAdditionalInfo())
+                                .append(ADD_INFO, additionalInfo)
                 ),
                 new UpdateOptions().upsert(true)
         );

caching/src/main/java/com/iluwatar/caching/database/VirtualDb.java

@@ -10,35 +10,61 @@ import java.util.Map;
  * implements base methods to work with hashMap as database.
  */
 public class VirtualDb implements DbManager {
+    /**
+     * Virtual DataBase.
+     */
     private Map<String, UserAccount> virtualDB;
 
+    /**
+     * Creates new HashMap.
+     */
     @Override
     public void connect() {
         virtualDB = new HashMap<>();
     }
 
+    /**
+     * Read from Db.
+     * @param userId {@link String}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount readFromDb(String userId) {
+    public UserAccount readFromDb(final String userId) {
         if (virtualDB.containsKey(userId)) {
             return virtualDB.get(userId);
         }
         return null;
     }
 
+    /**
+     * Write to DB.
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount writeToDb(UserAccount userAccount) {
+    public UserAccount writeToDb(final UserAccount userAccount) {
         virtualDB.put(userAccount.getUserId(), userAccount);
         return userAccount;
     }
 
+    /**
+     * Update reecord in DB.
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount updateDb(UserAccount userAccount) {
+    public UserAccount updateDb(final UserAccount userAccount) {
         virtualDB.put(userAccount.getUserId(), userAccount);
         return userAccount;
     }
 
+    /**
+     * Update.
+     * @param userAccount {@link UserAccount}
+     * @return {@link UserAccount}
+     */
     @Override
-    public UserAccount upsertDb(UserAccount userAccount) {
+    public UserAccount upsertDb(final UserAccount userAccount) {
         return updateDb(userAccount);
     }
 }

caching/src/main/java/com/iluwatar/caching/database/package-info.java

@@ -1,4 +1,4 @@
 /**
- * Database classes
+ * Database classes.
  */
 package com.iluwatar.caching.database;

caching/src/main/java/com/iluwatar/caching/package-info.java

@@ -1,4 +1,4 @@
-/*
+/**
  * The MIT License
  * Copyright © 2014-2021 Ilkka Seppälä
  *
@@ -20,5 +20,4 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
-
 package com.iluwatar.caching;