Resolves checkstyle errors for dao data-bus data-locality data-mapper…

… data-transfer-object decorator (#1067)

* Reduces checkstyle errors in dao

* Reduces checkstyle errors in data-bus

* Reduces checkstyle errors in data-locality

* Reduces checkstyle errors in data-mapper

* Reduces checkstyle errors in data-transfer-object

* Reduces checkstyle errors in decorator

dao/src/main/java/com/iluwatar/dao/App.java

@@ -26,12 +26,9 @@
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.sql.Statement;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.stream.Stream;
-
 import javax.sql.DataSource;
-
 import org.h2.jdbcx.JdbcDataSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -44,27 +41,25 @@
  * application needs, in terms of domain-specific objects and data types (the public interface of
  * the DAO), from how these needs can be satisfied with a specific DBMS.
  *
- * <p>With the DAO pattern, we can use various method calls to retrieve/add/delete/update data 
- * without directly interacting with the data source. The below example demonstrates basic CRUD 
+ * <p>With the DAO pattern, we can use various method calls to retrieve/add/delete/update data
+ * without directly interacting with the data source. The below example demonstrates basic CRUD
  * operations: select, add, update, and delete.
- * 
- * 
  */
 public class App {
   private static final String DB_URL = "jdbc:h2:~/dao";
   private static Logger log = LoggerFactory.getLogger(App.class);
   private static final String ALL_CUSTOMERS = "customerDao.getAllCustomers(): ";
-  
+
   /**
    * Program entry point.
-   * 
+   *
    * @param args command line args.
-   * @throws Exception if any error occurs. 
+   * @throws Exception if any error occurs.
    */
   public static void main(final String[] args) throws Exception {
     final CustomerDao inMemoryDao = new InMemoryCustomerDao();
     performOperationsUsing(inMemoryDao);
-    
+
     final DataSource dataSource = createDataSource();
     createSchema(dataSource);
     final CustomerDao dbDao = new DbCustomerDao(dataSource);
@@ -74,14 +69,14 @@ public static void main(final String[] args) throws Exception {
 
   private static void deleteSchema(DataSource dataSource) throws SQLException {
     try (Connection connection = dataSource.getConnection();
-        Statement statement = connection.createStatement()) {
+         Statement statement = connection.createStatement()) {
       statement.execute(CustomerSchemaSql.DELETE_SCHEMA_SQL);
     }
   }
 
   private static void createSchema(DataSource dataSource) throws SQLException {
     try (Connection connection = dataSource.getConnection();
-        Statement statement = connection.createStatement()) {
+         Statement statement = connection.createStatement()) {
       statement.execute(CustomerSchemaSql.CREATE_SCHEMA_SQL);
     }
   }
@@ -121,7 +116,7 @@ private static void addCustomers(CustomerDao customerDao) throws Exception {
 
   /**
    * Generate customers.
-   * 
+   *
    * @return list of customers.
    */
   public static List<Customer> generateSampleCustomers() {

dao/src/main/java/com/iluwatar/dao/CustomException.java

@@ -24,20 +24,19 @@
 package com.iluwatar.dao;
 
 /**
- * 
- * Custom exception
- *
+ * Custom exception.
  */
 public class CustomException extends Exception {
 
   private static final long serialVersionUID = 1L;
 
-  public CustomException() {}
+  public CustomException() {
+  }
 
   public CustomException(String message) {
     super(message);
   }
-  
+
   public CustomException(String message, Throwable cause) {
     super(message, cause);
   }

dao/src/main/java/com/iluwatar/dao/Customer.java

@@ -25,7 +25,6 @@
 
 /**
  * A customer POJO that represents the data that will be read from the data source.
- *
  */
 public class Customer {
 

dao/src/main/java/com/iluwatar/dao/CustomerDao.java

@@ -28,51 +28,61 @@
 
 /**
  * In an application the Data Access Object (DAO) is a part of Data access layer. It is an object
- * that provides an interface to some type of persistence mechanism. By mapping application calls
- * to the persistence layer, DAO provides some specific data operations without exposing details 
- * of the database. This isolation supports the Single responsibility principle. It separates what
- * data accesses the application needs, in terms of domain-specific objects and data types 
- * (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS,
- * database schema, etc.
- * 
- * <p>Any change in the way data is stored and retrieved will not change the client code as the 
+ * that provides an interface to some type of persistence mechanism. By mapping application calls to
+ * the persistence layer, DAO provides some specific data operations without exposing details of the
+ * database. This isolation supports the Single responsibility principle. It separates what data
+ * accesses the application needs, in terms of domain-specific objects and data types (the public
+ * interface of the DAO), from how these needs can be satisfied with a specific DBMS, database
+ * schema, etc.
+ *
+ * <p>Any change in the way data is stored and retrieved will not change the client code as the
  * client will be using interface and need not worry about exact source.
- * 
+ *
  * @see InMemoryCustomerDao
  * @see DbCustomerDao
  */
 public interface CustomerDao {
 
   /**
-   * @return all the customers as a stream. The stream may be lazily or eagerly evaluated based 
-   *     on the implementation. The stream must be closed after use.
+   * Get all customers.
+   *
+   * @return all the customers as a stream. The stream may be lazily or eagerly evaluated based on
+   *     the implementation. The stream must be closed after use.
    * @throws Exception if any error occurs.
    */
   Stream<Customer> getAll() throws Exception;
-  
+
   /**
+   * Get customer as Optional by id.
+   *
    * @param id unique identifier of the customer.
-   * @return an optional with customer if a customer with unique identifier <code>id</code>
-   *     exists, empty optional otherwise.
+   * @return an optional with customer if a customer with unique identifier <code>id</code> exists,
+   *     empty optional otherwise.
    * @throws Exception if any error occurs.
    */
   Optional<Customer> getById(int id) throws Exception;
 
   /**
+   * Add a customer.
+   *
    * @param customer the customer to be added.
    * @return true if customer is successfully added, false if customer already exists.
    * @throws Exception if any error occurs.
    */
   boolean add(Customer customer) throws Exception;
 
   /**
+   * Update a customer.
+   *
    * @param customer the customer to be updated.
    * @return true if customer exists and is successfully updated, false otherwise.
    * @throws Exception if any error occurs.
    */
   boolean update(Customer customer) throws Exception;
 
   /**
+   * Delete a customer.
+   *
    * @param customer the customer to be deleted.
    * @return true if customer exists and is successfully deleted, false otherwise.
    * @throws Exception if any error occurs.

dao/src/main/java/com/iluwatar/dao/CustomerSchemaSql.java

@@ -24,14 +24,16 @@
 package com.iluwatar.dao;
 
 /**
- * Customer Schema SQL Class
+ * Customer Schema SQL Class.
  */
 public final class CustomerSchemaSql {
 
-  private CustomerSchemaSql() {}
+  private CustomerSchemaSql() {
+  }
 
-  public static final String CREATE_SCHEMA_SQL = "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), "
-      + "LNAME VARCHAR(100))";
+  public static final String CREATE_SCHEMA_SQL =
+      "CREATE TABLE CUSTOMERS (ID NUMBER, FNAME VARCHAR(100), "
+          + "LNAME VARCHAR(100))";
 
   public static final String DELETE_SCHEMA_SQL = "DROP TABLE CUSTOMERS";
 

dao/src/main/java/com/iluwatar/dao/DbCustomerDao.java

@@ -23,9 +23,6 @@
 
 package com.iluwatar.dao;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
@@ -36,12 +33,12 @@
 import java.util.function.Consumer;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
-
 import javax.sql.DataSource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * An implementation of {@link CustomerDao} that persists customers in RDBMS.
- *
  */
 public class DbCustomerDao implements CustomerDao {
 
@@ -50,29 +47,32 @@ public class DbCustomerDao implements CustomerDao {
   private final DataSource dataSource;
 
   /**
-   * Creates an instance of {@link DbCustomerDao} which uses provided <code>dataSource</code>
-   * to store and retrieve customer information.
-   * 
+   * Creates an instance of {@link DbCustomerDao} which uses provided <code>dataSource</code> to
+   * store and retrieve customer information.
+   *
    * @param dataSource a non-null dataSource.
    */
   public DbCustomerDao(DataSource dataSource) {
     this.dataSource = dataSource;
   }
 
   /**
-   * @return a lazily populated stream of customers. Note the stream returned must be closed to 
-   *     free all the acquired resources. The stream keeps an open connection to the database till
-   *     it is complete or is closed manually.
+   * Get all customers as Java Stream.
+   *
+   * @return a lazily populated stream of customers. Note the stream returned must be closed to free
+   *     all the acquired resources. The stream keeps an open connection to the database till it is
+   *     complete or is closed manually.
    */
   @Override
   public Stream<Customer> getAll() throws Exception {
 
     Connection connection;
     try {
       connection = getConnection();
-      PreparedStatement statement = connection.prepareStatement("SELECT * FROM CUSTOMERS"); // NOSONAR
+      PreparedStatement statement =
+          connection.prepareStatement("SELECT * FROM CUSTOMERS"); // NOSONAR
       ResultSet resultSet = statement.executeQuery(); // NOSONAR
-      return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE, 
+      return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE,
           Spliterator.ORDERED) {
 
         @Override
@@ -108,8 +108,8 @@ private void mutedClose(Connection connection, PreparedStatement statement, Resu
   }
 
   private Customer createCustomer(ResultSet resultSet) throws SQLException {
-    return new Customer(resultSet.getInt("ID"), 
-        resultSet.getString("FNAME"), 
+    return new Customer(resultSet.getInt("ID"),
+        resultSet.getString("FNAME"),
         resultSet.getString("LNAME"));
   }
 
@@ -122,8 +122,8 @@ public Optional<Customer> getById(int id) throws Exception {
     ResultSet resultSet = null;
 
     try (Connection connection = getConnection();
-        PreparedStatement statement = 
-            connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
+         PreparedStatement statement =
+             connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
 
       statement.setInt(1, id);
       resultSet = statement.executeQuery();
@@ -151,8 +151,8 @@ public boolean add(Customer customer) throws Exception {
     }
 
     try (Connection connection = getConnection();
-        PreparedStatement statement = 
-            connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
+         PreparedStatement statement =
+             connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
       statement.setInt(1, customer.getId());
       statement.setString(2, customer.getFirstName());
       statement.setString(3, customer.getLastName());
@@ -169,8 +169,9 @@ public boolean add(Customer customer) throws Exception {
   @Override
   public boolean update(Customer customer) throws Exception {
     try (Connection connection = getConnection();
-        PreparedStatement statement = 
-            connection.prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
+         PreparedStatement statement =
+             connection
+                 .prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
       statement.setString(1, customer.getFirstName());
       statement.setString(2, customer.getLastName());
       statement.setInt(3, customer.getId());
@@ -186,8 +187,8 @@ public boolean update(Customer customer) throws Exception {
   @Override
   public boolean delete(Customer customer) throws Exception {
     try (Connection connection = getConnection();
-        PreparedStatement statement = 
-            connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
+         PreparedStatement statement =
+             connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
       statement.setInt(1, customer.getId());
       return statement.executeUpdate() > 0;
     } catch (SQLException ex) {

dao/src/main/java/com/iluwatar/dao/InMemoryCustomerDao.java

@@ -29,8 +29,8 @@
 import java.util.stream.Stream;
 
 /**
- * An in memory implementation of {@link CustomerDao}, which stores the customers in JVM memory
- * and data is lost when the application exits.
+ * An in memory implementation of {@link CustomerDao}, which stores the customers in JVM memory and
+ * data is lost when the application exits.
  * <br>
  * This implementation is useful as temporary database or for testing.
  */
@@ -56,7 +56,7 @@ public boolean add(final Customer customer) {
     if (getById(customer.getId()).isPresent()) {
       return false;
     }
-    
+
     idToCustomer.put(customer.getId(), customer);
     return true;
   }