Java 11 migrate c-d (remaining) (#1111)

* Moves converter pattern to Java 11

* Moves cqrs pattern to Java 11

* Moves dao pattern to Java 11

* Moves data-bus pattern to Java 11

* Moves data-locality pattern to Java 11

* Moves data-mapper pattern to Java 11

* Moves data-transfer-object pattern to Java 11

* Moves decorator pattern to Java 11

* Moves delegation pattern to Java 11

* Moves dependency-injection to Java 11

* Moves dirty-flag to Java 11

* Moves double-buffer to Java 11

* Moves double-checked-locking to Java 11

* Moves double-dispatch to Java 11

* Corrects with changes thats breaking test cases

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

@@ -23,11 +23,8 @@
 
 package com.iluwatar.dao;
 
-import java.sql.Connection;
 import java.sql.SQLException;
-import java.sql.Statement;
 import java.util.List;
-import java.util.stream.Stream;
 import javax.sql.DataSource;
 import org.h2.jdbcx.JdbcDataSource;
 import org.slf4j.Logger;
@@ -57,32 +54,32 @@ public class App {
    * @throws Exception if any error occurs.
    */
   public static void main(final String[] args) throws Exception {
-    final CustomerDao inMemoryDao = new InMemoryCustomerDao();
+    final var inMemoryDao = new InMemoryCustomerDao();
     performOperationsUsing(inMemoryDao);
 
-    final DataSource dataSource = createDataSource();
+    final var dataSource = createDataSource();
     createSchema(dataSource);
-    final CustomerDao dbDao = new DbCustomerDao(dataSource);
+    final var dbDao = new DbCustomerDao(dataSource);
     performOperationsUsing(dbDao);
     deleteSchema(dataSource);
   }
 
   private static void deleteSchema(DataSource dataSource) throws SQLException {
-    try (Connection connection = dataSource.getConnection();
-         Statement statement = connection.createStatement()) {
+    try (var connection = dataSource.getConnection();
+         var 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()) {
+    try (var connection = dataSource.getConnection();
+         var statement = connection.createStatement()) {
       statement.execute(CustomerSchemaSql.CREATE_SCHEMA_SQL);
     }
   }
 
   private static DataSource createDataSource() {
-    JdbcDataSource dataSource = new JdbcDataSource();
+    var dataSource = new JdbcDataSource();
     dataSource.setURL(DB_URL);
     return dataSource;
   }
@@ -90,18 +87,18 @@ public class App {
   private static void performOperationsUsing(final CustomerDao customerDao) throws Exception {
     addCustomers(customerDao);
     log.info(ALL_CUSTOMERS);
-    try (Stream<Customer> customerStream = customerDao.getAll()) {
+    try (var customerStream = customerDao.getAll()) {
       customerStream.forEach((customer) -> log.info(customer.toString()));
     }
     log.info("customerDao.getCustomerById(2): " + customerDao.getById(2));
-    final Customer customer = new Customer(4, "Dan", "Danson");
+    final var customer = new Customer(4, "Dan", "Danson");
     customerDao.add(customer);
     log.info(ALL_CUSTOMERS + customerDao.getAll());
     customer.setFirstName("Daniel");
     customer.setLastName("Danielson");
     customerDao.update(customer);
     log.info(ALL_CUSTOMERS);
-    try (Stream<Customer> customerStream = customerDao.getAll()) {
+    try (var customerStream = customerDao.getAll()) {
       customerStream.forEach((cust) -> log.info(cust.toString()));
     }
     customerDao.delete(customer);
@@ -109,7 +106,7 @@ public class App {
   }
 
   private static void addCustomers(CustomerDao customerDao) throws Exception {
-    for (Customer customer : generateSampleCustomers()) {
+    for (var customer : generateSampleCustomers()) {
       customerDao.add(customer);
     }
   }
@@ -120,9 +117,9 @@ public class App {
    * @return list of customers.
    */
   public static List<Customer> generateSampleCustomers() {
-    final Customer customer1 = new Customer(1, "Adam", "Adamson");
-    final Customer customer2 = new Customer(2, "Bob", "Bobson");
-    final Customer customer3 = new Customer(3, "Carl", "Carlson");
+    final var customer1 = new Customer(1, "Adam", "Adamson");
+    final var customer2 = new Customer(2, "Bob", "Bobson");
+    final var customer3 = new Customer(3, "Carl", "Carlson");
     return List.of(customer1, customer2, customer3);
   }
 }

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

@@ -73,11 +73,11 @@ public class Customer {
 
   @Override
   public boolean equals(final Object that) {
-    boolean isEqual = false;
+    var isEqual = false;
     if (this == that) {
       isEqual = true;
     } else if (that != null && getClass() == that.getClass()) {
-      final Customer customer = (Customer) that;
+      final var customer = (Customer) that;
       if (getId() == customer.getId()) {
         isEqual = true;
       }

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

@@ -65,13 +65,10 @@ public class DbCustomerDao implements CustomerDao {
    */
   @Override
   public Stream<Customer> getAll() throws Exception {
-
-    Connection connection;
     try {
-      connection = getConnection();
-      PreparedStatement statement =
-          connection.prepareStatement("SELECT * FROM CUSTOMERS"); // NOSONAR
-      ResultSet resultSet = statement.executeQuery(); // NOSONAR
+      var connection = getConnection();
+      var statement = connection.prepareStatement("SELECT * FROM CUSTOMERS");
+      var resultSet = statement.executeQuery(); // NOSONAR
       return StreamSupport.stream(new Spliterators.AbstractSpliterator<Customer>(Long.MAX_VALUE,
           Spliterator.ORDERED) {
 
@@ -121,9 +118,8 @@ public class DbCustomerDao implements CustomerDao {
 
     ResultSet resultSet = null;
 
-    try (Connection connection = getConnection();
-         PreparedStatement statement =
-             connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
+    try (var connection = getConnection();
+         var statement = connection.prepareStatement("SELECT * FROM CUSTOMERS WHERE ID = ?")) {
 
       statement.setInt(1, id);
       resultSet = statement.executeQuery();
@@ -150,9 +146,8 @@ public class DbCustomerDao implements CustomerDao {
       return false;
     }
 
-    try (Connection connection = getConnection();
-         PreparedStatement statement =
-             connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
+    try (var connection = getConnection();
+         var statement = connection.prepareStatement("INSERT INTO CUSTOMERS VALUES (?,?,?)")) {
       statement.setInt(1, customer.getId());
       statement.setString(2, customer.getFirstName());
       statement.setString(3, customer.getLastName());
@@ -168,8 +163,8 @@ public class DbCustomerDao implements CustomerDao {
    */
   @Override
   public boolean update(Customer customer) throws Exception {
-    try (Connection connection = getConnection();
-         PreparedStatement statement =
+    try (var connection = getConnection();
+         var statement =
              connection
                  .prepareStatement("UPDATE CUSTOMERS SET FNAME = ?, LNAME = ? WHERE ID = ?")) {
       statement.setString(1, customer.getFirstName());
@@ -186,9 +181,8 @@ public class DbCustomerDao implements CustomerDao {
    */
   @Override
   public boolean delete(Customer customer) throws Exception {
-    try (Connection connection = getConnection();
-         PreparedStatement statement =
-             connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
+    try (var connection = getConnection();
+         var statement = connection.prepareStatement("DELETE FROM CUSTOMERS WHERE ID = ?")) {
       statement.setInt(1, customer.getId());
       return statement.executeUpdate() > 0;
     } catch (SQLException ex) {