Merge remote-tracking branch 'origin/johannes2' into julian2

# Conflicts:
#	src/main/java/de/hsel/itech/db/Database.java

checkstyle.xml

@@ -44,7 +44,7 @@
             <property name="allowNonPrintableEscapes" value="true"/>
         </module>
         <module name="LineLength">
-            <property name="max" value="100"/>
+            <property name="max" value="200"/>
             <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
         </module>
         <module name="AvoidStarImport"/>
@@ -55,13 +55,14 @@
             <property name="tokens"
                       value="LITERAL_TRY, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE, LITERAL_SWITCH"/>
         </module>
-        <module name="NeedBraces"/>
+        <module name="NeedBraces">
+            <property name="tokens" value="LITERAL_DO"/>
+        </module>
         <module name="LeftCurly"/>
         <module name="RightCurly">
             <property name="id" value="RightCurlySame"/>
             <property name="tokens"
-                      value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_IF, LITERAL_ELSE,
+                      value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_DO, LITERAL_IF, LITERAL_ELSE"/>
-                    LITERAL_DO"/>
         </module>
         <module name="RightCurly">
             <property name="id" value="RightCurlyAlone"/>

pom.xml

@@ -212,6 +212,10 @@
                 <artifactId>spotbugs-maven-plugin</artifactId>
                 <version>3.1.9</version>
             </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+            </plugin>
         </plugins>
     </reporting>
 

src/main/java/de/hsel/itech/config/Configuration.java

@@ -10,6 +10,8 @@ import java.io.FileNotFoundException;
 import java.io.FileReader;
 
 /**
+ * config object.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -25,7 +27,10 @@ public class Configuration {
     private Database database;
 
 
-
+    /**
+     * gets Configuration object from file.
+     * @return {@link de.hsel.itech.config.Configuration}
+     */
     public static Configuration get() {
         Gson gson = new Gson();
 

src/main/java/de/hsel/itech/config/Database.java

@@ -5,6 +5,8 @@ import lombok.Getter;
 import lombok.ToString;
 
 /**
+ * POJO for gson.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1

src/main/java/de/hsel/itech/db/Database.java

@@ -5,21 +5,26 @@ import de.hsel.itech.db.pojo.Author;
 import de.hsel.itech.db.pojo.Book;
 import de.hsel.itech.db.pojo.Category;
 import de.hsel.itech.db.pojo.Publisher;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.mariadb.jdbc.MariaDbPoolDataSource;
 
 import java.io.BufferedReader;
 import java.io.FileReader;
 import java.io.IOException;
+import java.net.URL;
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.time.Year;
+import java.util.AbstractMap;
 import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
 
 /**
- *
+ * base class for everything regarding the database.
  *
  * @author Johannes Theiner
  * @version 0.1
@@ -27,19 +32,34 @@ import java.util.ArrayList;
  */
 public class Database {
 
+    private final String book = "book";
+    private final String author = "author";
+    private final String authorBook = "author_book";
+    private final String publisher = "publisher";
+    private final String category = "category";
+
     private static Database instance;
 
+    /**
+     * Singleton for database access.
+     *
+     * @return {@link Database}
+     */
     public static Database getInstance() {
-        if(instance == null)
+        if (instance == null)
             instance = new Database();
         return instance;
     }
 
     private MariaDbPoolDataSource dataSource;
 
+    /**
+     * initializes connection pool and executes database setup.
+     */
     private Database() {
         Configuration config = Configuration.get();
-        dataSource = new MariaDbPoolDataSource("jdbc:mysql://" + config.getDatabase().getHostname() + ":" + config.getDatabase().getPort() + "/" + config.getDatabase().getDatabase());
+        dataSource = new MariaDbPoolDataSource("jdbc:mysql://" + config.getDatabase().getHostname()
+                + ":" + config.getDatabase().getPort() + "/" + config.getDatabase().getDatabase());
         try {
             dataSource.setUser(config.getDatabase().getUsername());
             dataSource.setPassword(config.getDatabase().getPassword());
@@ -47,7 +67,9 @@ public class Database {
 
             Connection connection = getConnection();
             assert connection != null;
-            try(BufferedReader br = new BufferedReader(new FileReader(getClass().getClassLoader().getResource("database.sql").getFile()))) {
+            URL file = getClass().getClassLoader().getResource("database.sql");
+            assert file != null;
+            try (BufferedReader br = new BufferedReader(new FileReader(file.getFile()))) {
                 for (String line = br.readLine(); line != null; line = br.readLine()) {
                     PreparedStatement statement = connection.prepareStatement(line);
                     statement.executeUpdate();
@@ -55,8 +77,7 @@ public class Database {
                 }
             } catch (IOException e) {
                 e.printStackTrace();
-            }
+            } finally {
-            finally {
                 connection.close();
             }
         } catch (SQLException e) {
@@ -64,6 +85,11 @@ public class Database {
         }
     }
 
+    /**
+     * gets connection from connection pool.
+     *
+     * @return {@link java.sql.Connection}
+     */
     @Nullable
     private Connection getConnection() {
         try {
@@ -74,6 +100,12 @@ public class Database {
         return null;
     }
 
+    /**
+     * testing method.
+     *
+     * @return String
+     */
+    @Deprecated
     public String getHello() {
         Connection connection = getConnection();
 
@@ -82,63 +114,497 @@ public class Database {
             assert connection != null;
             PreparedStatement statement = connection.prepareStatement("SELECT * FROM test WHERE id = 1");
             ResultSet resultSet = statement.executeQuery();
-            resultSet.next();
+            if (resultSet.next())
                 hello = resultSet.getString("hello");
 
             connection.close();
         } catch (SQLException e) {
             e.printStackTrace();
         }
-
         return hello;
-
     }
 
+    /**
+     * gets author by id.
+     *
+     * @param id ID from database
+     * @return {@link de.hsel.itech.db.pojo.Author}
+     */
+    @Nullable
+    public Author getAuthor(long id) {
+        Map.Entry<ResultSet, Connection> entry = getResultSet(id, author);
+        assert entry != null;
 
-    private ArrayList<Book> books;
+        ResultSet rs = entry.getKey();
-
+        Author author = null;
-    public void addBook(Book book){
+        try {
-        if(books == null){
+            author = new Author(rs.getLong("id"), rs.getString("name"));
-            books = new ArrayList<Book>();
+            entry.getValue().close();
+        } catch (SQLException e) {
+            e.printStackTrace();
         }
-        books.add(book);
+        return author;
     }
 
-    public void removeBook(long isbn){
+    /**
-        for(Book book : books){
+     * gets category by id.
-            if(book.getIsbn() == isbn){
+     *
-                books.remove(book);
+     * @param id ID from database
-                break;
+     * @return {@link de.hsel.itech.db.pojo.Category}
-            }
+     */
+    @Nullable
+    public Category getCategory(long id) {
+        Map.Entry<ResultSet, Connection> entry = getResultSet(id, category);
+        assert entry != null;
+
+        ResultSet rs = entry.getKey();
+        Category category = null;
+        try {
+            category = new Category(rs.getLong("id"), rs.getString("name"), rs.getString("image"));
+            entry.getValue().close();
+        } catch (SQLException e) {
+            e.printStackTrace();
         }
+        return category;
     }
 
-    public ArrayList<Book> getBooks(){
+    /**
-        if(books == null){
+     * gets publisher by id.
-            books = new ArrayList<Book>();
+     *
-            Book book = new Book(
+     * @param id ID from database
-                    1234,
+     * @return {@link de.hsel.itech.db.pojo.Publisher}
-                    new Author(123123,"Julian Hinxlage"),
+     */
-                    new Publisher(234231,"Verlag xy"),
+    @Nullable
-                    new Category(23434,"Education", "DxAzOKSiPoE"),
+    public Publisher getPublisher(long id) {
-                    "C++ for beginners", Year.of(2019),1500,"C++ book", "DxAzOKSiPoE"
+        Map.Entry<ResultSet, Connection> entry = getResultSet(id, publisher);
-            );
+        assert entry != null;
-            books.add(book);
 
-            book = new Book(
+        ResultSet rs = entry.getKey();
-                    1235,
+        Publisher publisher = null;
-                    new Author(123123,"Julian Hinxlage"),
+        try {
-                    new Publisher(234231,"Verlag xy"),
+            publisher = new Publisher(rs.getLong("id"), rs.getString("name"));
-                    new Category(23434,"Education", "DxAzOKSiPoE"),
+            entry.getValue().close();
-                    "C++ for beginners vol 2", Year.of(2019),1499,"C++ book", "DxAzOKSiPoE"
+        } catch (SQLException e) {
-            );
+            e.printStackTrace();
-            books.add(book);
+        }
+        return publisher;
     }
 
+    /**
+     * gets list of author ids from database.
+     *
+     * @param id book id from database
+     * @return {@link java.util.List}
+     */
+    @Nullable
+    private List<Integer> getAuthors(long id) {
+        Map.Entry<List<ResultSet>, Connection> entry = getResultSets(id, authorBook, book);
+        assert entry != null;
+        try {
+            List<Integer> list = new ArrayList<>();
+            for (ResultSet rs : entry.getKey()) {
+                list.add(rs.getInt(author));
+            }
+            entry.getValue().close();
+            return list;
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return null;
+    }
+
+    /**
+     * gets book by id.
+     *
+     * @param id ID from database
+     * @return {@link de.hsel.itech.db.pojo.Book}
+     */
+    @Nullable
+    public Book getBook(long id) {
+        Map.Entry<ResultSet, Connection> entry = getResultSet(id, book);
+        assert entry != null;
+
+        ResultSet rs = entry.getKey();
+        Book book = null;
+        try {
+            Category category = getCategory(rs.getLong(this.category));
+            Publisher publisher = getPublisher(rs.getLong(this.publisher));
+            List<Integer> authorIds = getAuthors(id);
+            assert authorIds != null;
+            List<Author> authors = new ArrayList<>();
+            for (int i : authorIds) {
+                Author author = getAuthor(i);
+                assert author != null;
+                authors.add(author);
+            }
+            book = new Book(rs.getLong("id"), authors, publisher, category, rs.getString("title"),
+                    Year.of(rs.getInt("year")), rs.getInt("price"), rs.getString("description"),
+                    rs.getString("image"));
+            entry.getValue().close();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return book;
+    }
+
+    /**
+     * gets all books.
+     *
+     * @return {@link java.util.List}
+     */
+    @Nullable
+    public List<Book> getBooks() {
+        Map.Entry<List<ResultSet>, Connection> entry = getResultSets(book, "id");
+        assert entry != null;
+
+        List<Long> ids = new ArrayList<>();
+        try {
+            for (ResultSet resultSet : entry.getKey()) {
+                ids.add(resultSet.getLong("id"));
+            }
+            entry.getValue().close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        List<Book> books = new ArrayList<>();
+        for (long id : ids) {
+            books.add(getBook(id));
+        }
         return books;
     }
 
+    /**
+     * gets books by category.
+     *
+     * @param category category id
+     * @return {@link java.util.List}
+     */
+    @Nullable
+    public List<Book> getBooks(long category) {
+        Connection connection = getConnection();
+        assert connection != null;
+
+        List<Book> books = new ArrayList<>();
+        try {
+            PreparedStatement statement = connection.prepareStatement("SELECT (id) FROM book WHERE category = ?");
+            statement.setLong(1, category);
+
+            ResultSet resultSet = statement.executeQuery();
+
+            while (resultSet.next()) {
+                books.add(getBook(resultSet.getLong("id")));
+            }
+
+            connection.close();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        return books;
+    }
+
+    /**
+     * get books by category.
+     *
+     * @param category Category object
+     * @return {@link java.util.List}
+     */
+    @Nullable
+    public List<Book> getBooks(@NotNull Category category) {
+        return getBooks(category.getId());
+    }
 
 
+    /**
+     * Inserts book into database.
+     * authors, publishers, and category have to exist.
+     *
+     * @param book Book
+     * @return insert count
+     */
+    public int insert(@NotNull Book book) {
+        Connection connection = getConnection();
+        assert connection != null;
 
+        int insertCount = 0;
+
+        try {
+            PreparedStatement statement = connection.prepareStatement("INSERT INTO book(title, description, "
+                    + "price, year, publisher, category, image) VALUES (?, ?, ?, ?, ?, ?, ?)");
+            statement.setString(1, book.getTitle());
+            statement.setString(2, book.getDescription());
+            statement.setInt(3, book.getPrice());
+            statement.setInt(4, book.getYear().getValue());
+            statement.setLong(5, book.getPublisher().getId());
+            statement.setLong(6, book.getCategory().getId());
+            statement.setString(7, book.getImage());
+            insertCount += statement.executeUpdate();
+
+            for (Author author : book.getAuthors()) {
+                PreparedStatement authorStatement = connection.prepareStatement("INSERT INTO author_book (author, book) VALUES (?, ?)");
+                statement.setLong(1, author.getId());
+                statement.setLong(2, book.getIsbn());
+                insertCount += authorStatement.executeUpdate();
+            }
+
+            connection.close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return insertCount;
+    }
+
+    /**
+     * inserts Category into database.
+     *
+     * @param category Category
+     * @return insert count
+     */
+    public int insert(@NotNull Category category) {
+        Connection connection = getConnection();
+        assert connection != null;
+
+        int insertCount = 0;
+
+        try {
+            PreparedStatement statement = connection.prepareStatement("INSERT INTO category (name, image) VALUES (?, ?)");
+            statement.setString(1, category.getName());
+            statement.setString(2, category.getImage());
+            insertCount += statement.executeUpdate();
+
+            connection.close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return insertCount;
+    }
+
+    /**
+     * inserts Author.
+     *
+     * @param author Author
+     * @return insert count
+     */
+    public int insert(@NotNull Author author) {
+        Connection connection = getConnection();
+        assert connection != null;
+
+        int insertCount = 0;
+        try {
+            PreparedStatement statement = connection.prepareStatement("INSERT INTO author (name) VALUES (?)");
+            statement.setString(1, author.getName());
+
+            insertCount += statement.executeUpdate();
+
+            connection.close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return insertCount;
+    }
+
+    /**
+     * inserts Publisher.
+     *
+     * @param publisher Publisher
+     * @return insert count
+     */
+    public int insert(@NotNull Publisher publisher) {
+        Connection connection = getConnection();
+        assert connection != null;
+
+        int insertCount = 0;
+        try {
+            PreparedStatement statement = connection.prepareStatement("INSERT INTO publisher (name) VALUES (?)");
+            statement.setString(1, publisher.getName());
+
+            insertCount += statement.executeUpdate();
+
+            connection.close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return insertCount;
+    }
+
+    /**
+     * deletes book from database.
+     *
+     * @param id book id
+     * @return deletion count
+     */
+    public int deleteBook(long id) {
+        int deleteCount = 0;
+
+        try {
+            Connection connection = getConnection();
+            assert connection != null;
+
+            PreparedStatement statement = connection.prepareStatement("DELETE FROM author_book WHERE book = ?");
+            statement.setLong(1, id);
+            deleteCount = +statement.executeUpdate();
+
+            connection.close();
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+
+        deleteCount += delete(id, book);
+
+        return deleteCount;
+    }
+
+    /**
+     * deletes author from database.
+     *
+     * @param id author id
+     * @return deletion count
+     */
+    public int deleteAuthor(long id) {
+        return delete(id, author);
+    }
+
+    /**
+     * deletes publisher from database.
+     *
+     * @param id publisher id
+     * @return deletion count
+     */
+    public int deletePublisher(long id) {
+        return delete(id, publisher);
+    }
+
+    /**
+     * deletes category from database.
+     *
+     * @param id category count
+     * @return deletion count
+     */
+    public int deleteCategory(long id) {
+        return delete(id, category);
+    }
+
+
+    /**
+     * deletes id from table.
+     *
+     * @param id    database id
+     * @param table table name
+     * @return deletion count
+     */
+    private int delete(long id, String table) {
+        Connection connection = getConnection();
+        assert connection != null;
+
+        int deleteCount = 0;
+        try {
+            PreparedStatement statement = connection.prepareStatement("DELETE FROM ? WHERE id=?");
+            statement.setString(1, table);
+            statement.setLong(2, id);
+
+            deleteCount = +statement.executeUpdate();
+
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return deleteCount;
+    }
+
+
+    /**
+     * gets specific entry from database.
+     *
+     * @param id    id from database
+     * @param table table name
+     * @return {@link java.util.Map.Entry}
+     */
+    @Nullable
+    private Map.Entry<ResultSet, Connection> getResultSet(long id, String table) {
+        Connection connection = getConnection();
+        try {
+            assert connection != null;
+            PreparedStatement statement = connection.prepareStatement("SELECT * FROM ? WHERE ID = ?");
+            statement.setString(1, table);
+            statement.setLong(2, id);
+            ResultSet resultSet = statement.executeQuery();
+            if (resultSet.next()) {
+                return new AbstractMap.SimpleEntry<>(resultSet, connection);
+            }
+            return null;
+
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return null;
+    }
+
+    /**
+     * gets specific entries from table.
+     *
+     * @param id     id all entries should reference
+     * @param table  table name
+     * @param column column to match
+     * @return {@link java.util.Map.Entry}
+     */
+    @Nullable
+    private Map.Entry<List<ResultSet>, Connection> getResultSets(long id, @NotNull String table, @NotNull String column) {
+        Connection connection = getConnection();
+        try {
+            assert connection != null;
+            PreparedStatement statement = connection.prepareStatement("SELECT * FROM ? WHERE ? = ?");
+            statement.setString(1, table);
+            statement.setString(2, column);
+            statement.setLong(3, id);
+
+            return getAllEntries(connection, statement);
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return null;
+    }
+
+    /**
+     * gets all specified columns from table.
+     *
+     * @param table   table name
+     * @param columns columns as String array
+     * @return {@link java.util.Map.Entry}
+     */
+    @Nullable
+    private Map.Entry<List<ResultSet>, Connection> getResultSets(@NotNull String table, @NotNull String... columns) {
+        Connection connection = getConnection();
+        try {
+            assert connection != null;
+            PreparedStatement statement = connection.prepareStatement("SELECT (?) FROM ?");
+            statement.setString(1, String.join(",", columns));
+            statement.setString(2, table);
+
+            return getAllEntries(connection, statement);
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return null;
+    }
+
+    /**
+     * gets all entries contained in result set.
+     *
+     * @param connection Connection
+     * @param statement  query statement
+     * @return {@link java.util.Map.Entry}
+     */
+    @Nullable
+    private Map.Entry<List<ResultSet>, Connection> getAllEntries(@NotNull Connection connection, @NotNull PreparedStatement statement) {
+        try {
+            ResultSet resultSet = statement.executeQuery();
+
+            Map.Entry<List<ResultSet>, Connection> entry = new AbstractMap.SimpleEntry<>(new ArrayList<>(), connection);
+            while (resultSet.next()) {
+                entry.getKey().add(resultSet);
+            }
+            return entry;
+        } catch (SQLException ex) {
+            ex.printStackTrace();
+        }
+        return null;
+    }
 }

src/main/java/de/hsel/itech/db/pojo/Address.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Address.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,13 +15,14 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Address {
 
-    private Customer customer;
+    @NonNull private Customer customer;
     private long id;
-    private String name;
+    @NonNull private String name;
-    private String street;
+    @NonNull private String street;
-    private String number;
+    @NonNull private String number;
-    private int zipCode;
+    @NonNull private int zipCode;
-    private String city;
+    @NonNull private String city;
 }

src/main/java/de/hsel/itech/db/pojo/Author.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Author.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,9 +15,10 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Author {
 
     private long id;
-    private String name;
+    @NonNull private String name;
 
 }

src/main/java/de/hsel/itech/db/pojo/Book.java

@@ -2,10 +2,15 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 import java.time.Year;
+import java.util.List;
 
 /**
+ * POJO for Book.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -13,21 +18,22 @@ import java.time.Year;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Book {
 
-    private int isbn;
+    private long isbn;
-    private Author author;
+    @NonNull private List<Author> authors;
-    private Publisher publisher;
+    @NonNull private Publisher publisher;
-    private Category category;
+    @NonNull private Category category;
-    private String title;
+    @NonNull private String title;
-    private Year year;
+    @NonNull private Year year;
 
     /**
-     * saved in cents
+     * saved in cents.
      */
-    private int price;
+    @NonNull private int price;
-    private String description;
+    @NonNull private String description;
-    private String image;
+    @NonNull private String image;
 
 
 

src/main/java/de/hsel/itech/db/pojo/Category.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Category.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,9 +15,10 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Category {
 
-    private int id;
+    private long id;
-    private String name;
+    @NonNull private String name;
-    private String image;
+    @NonNull private String image;
 }

src/main/java/de/hsel/itech/db/pojo/CreditCardPayment.java

@@ -2,10 +2,14 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 import java.time.LocalDate;
 
 /**
+ * POJO for CreditCard Payment.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -13,12 +17,13 @@ import java.time.LocalDate;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class CreditCardPayment {
 
     private long id;
-    private Customer customer;
+    @NonNull private Customer customer;
-    private int number;
+    @NonNull private int number;
-    private String owner;
+    @NonNull private String owner;
-    private LocalDate expiration;
+    @NonNull private LocalDate expiration;
-    private int checksum;
+    @NonNull private int checksum;
 }

src/main/java/de/hsel/itech/db/pojo/Customer.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Customer.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,11 +15,12 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Customer {
 
     private long id;
-    private String email;
+    @NonNull private String email;
-    private String name;
+    @NonNull private String name;
-    private String password;
+    @NonNull private String password;
-    private boolean admin;
+    @NonNull private boolean admin;
 }

src/main/java/de/hsel/itech/db/pojo/DebitCardPayment.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for DebitCard Payment.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,11 +15,12 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class DebitCardPayment {
 
     private long id;
-    private Customer customer;
+    @NonNull private Customer customer;
-    private String iban;
+    @NonNull private String iban;
-    private String bic;
+    @NonNull private String bic;
-    private String owner;
+    @NonNull private String owner;
 }

src/main/java/de/hsel/itech/db/pojo/InvoicePayment.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Invoice Payment.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,8 +15,9 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class InvoicePayment {
 
     private long id;
-    private Customer customer;
+    @NonNull private Customer customer;
 }

src/main/java/de/hsel/itech/db/pojo/Order.java

@@ -2,11 +2,15 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 import java.time.LocalDateTime;
 
 
 /**
+ * POJO for Orders.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -14,16 +18,17 @@ import java.time.LocalDateTime;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Order {
 
     private long id;
-    private LocalDateTime date;
+    @NonNull private LocalDateTime date;
-    private Book book;
+    @NonNull private Book book;
 
     /**
-     * price in cents
+     * price in cents.
      */
-    private int price;
+    @NonNull private int price;
-    private PaymentType paymentType;
+    @NonNull private PaymentType paymentType;
-    private Address address;
+    @NonNull private Address address;
 }

src/main/java/de/hsel/itech/db/pojo/PayPalPayment.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for PayPal Payment.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,10 +15,11 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class PayPalPayment {
 
     private long id;
-    private Customer customer;
+    @NonNull private Customer customer;
-    private String email;
+    @NonNull private String email;
-    private String authCode;
+    @NonNull private String authCode;
 }

src/main/java/de/hsel/itech/db/pojo/PaymentType.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for PaymentType.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,8 +15,9 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class PaymentType {
 
     private long id;
-    private String name;
+    @NonNull private String name;
 }

src/main/java/de/hsel/itech/db/pojo/Publisher.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Publisher.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,8 +15,9 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class Publisher {
 
     private long id;
-    private String name;
+    @NonNull private String name;
 }

src/main/java/de/hsel/itech/db/pojo/ShoppingCart.java

@@ -2,8 +2,12 @@ package de.hsel.itech.db.pojo;
 
 import lombok.AllArgsConstructor;
 import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
 
 /**
+ * POJO for Shopping Cart.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
@@ -11,10 +15,11 @@ import lombok.Data;
 
 @Data
 @AllArgsConstructor
+@RequiredArgsConstructor
 public class ShoppingCart {
 
     private long id;
-    private Customer customer;
+    @NonNull private Customer customer;
-    private Book article;
+    @NonNull private Book article;
-    private int count;
+    @NonNull private int count;
 }

src/main/java/de/hsel/itech/servlet/DbTest.java

@@ -1,5 +1,7 @@
 package de.hsel.itech.servlet;
 
+import de.hsel.itech.db.Database;
+
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -7,11 +9,13 @@ import java.io.IOException;
 import java.io.PrintWriter;
 
 /**
+ * Database test.
+ *
  * @author Johannes Theiner
  * @version 0.1
  * @since 0.1
  **/
-public class Database extends HttpServlet {
+public class DbTest extends HttpServlet {
 
     private static final long serialVersionUID = 15679036734L;
 
@@ -33,7 +37,7 @@ public class Database extends HttpServlet {
         out.println("<title>Hallo Welt!</title>");
         out.println("</head>");
         out.println("<body>");
-        out.println("<h1>" + de.hsel.itech.db.Database.getInstance().getHello() + "</h1>");
+        out.println("<h1>" + Database.getInstance().getHello() + "</h1>");
         out.println("</body>");
         out.println("</html>");
     }

src/main/webapp/WEB-INF/web.xml

@@ -12,7 +12,7 @@
 
     <servlet>
         <servlet-name>database</servlet-name>
-        <servlet-class>de.hsel.itech.servlet.Database</servlet-class>
+        <servlet-class>de.hsel.itech.servlet.DbTest</servlet-class>
     </servlet>
 
     <servlet>