Home work #405
Home work #405
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Great job on following best practices and adhering to Java conventions! Your implementation of the BookDao interface, the DataProcessingException class, and the Book class is spot-on. Keep up the good work, and remember to always secure sensitive information and handle exceptions gracefully. Your attention to detail is commendable. 🌟 Keep it up!
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src/main/java/mate/academy/Main.java
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| Book updatedBook = bookDao.findAll().stream() | ||
| .filter(b -> Objects.equals(b.getTitle(), "Effective Java")) | ||
| .findFirst() | ||
| .get(); |
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This code may throw a NoSuchElementException if 'findFirst()' doesn't find any element. It's better to use 'ifPresent()' after 'findFirst()' to check if the book is present before calling 'get()'.
src/main/java/mate/academy/Main.java
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| private static List<Book> books = List.of( | ||
| new Book("Core Java Volume I – Fundamentals", BigDecimal.valueOf(29.99)), | ||
| new Book("Effective Java", BigDecimal.valueOf(19.99)), | ||
| new Book("Java - The Complete Reference", BigDecimal.valueOf(35.45))); |
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Avoid using hard-coded values for books in the main method. It's better to move this to a separate method or class responsible for initializing data, or even better, to use a database script.
src/main/java/mate/academy/Main.java
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| //delete | ||
| books = bookDao.findAll(); |
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Calling 'bookDao.findAll()' multiple times is inefficient and can lead to performance issues. You should call it once and reuse the result.
| try (Connection connection = ConnectionUtil.getConnection(); | ||
| PreparedStatement statement | ||
| = connection.prepareStatement(query, Statement.RETURN_GENERATED_KEYS)) { |
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Use PreparedStatement over Statement, even for a static query with no parameters in findAll() method. It's the best practice, and it's slightly faster. In this case, you have used PreparedStatement correctly, but make sure to apply this practice consistently across all methods.
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2, book.getPrice()); | ||
| statement.setLong(3, book.getId()); | ||
| return book; |
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You should execute statement.executeUpdate() in the update method to actually perform the update operation on the database. Without this call, the update will not be applied.
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| @Override | ||
| public Book update(Book book) { | ||
| String query = "UPDATE books SET title = ?, price = ? WHERE id= ?;"; |
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Remember to use uppercase for SQL keywords in your queries for consistency and readability. The update query should have UPDATE, SET, and WHERE in uppercase.
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| @Override | ||
| public boolean deleteById(Long id) { | ||
| String query = "DELETE FROM books WHERE id = ?"; |
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Remember to use uppercase for SQL keywords in your queries for consistency and readability. The delete query should have DELETE and WHERE in uppercase.
| import java.util.Properties; | ||
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| public class ConnectionUtil { | ||
| private static final String URL = "jdbc:mysql://localhost:3306/library_service"; |
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The URL for the JDBC connection is incomplete. It should specify the database you're connecting to, for example, 'jdbc:mysql://localhost:3306/myDatabase'.
| import java.util.Properties; | ||
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| public class ConnectionUtil { | ||
| private static final String URL = "jdbc:mysql://localhost:3306/library_service"; |
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Avoid using hard-coded database credentials in your code. Consider using environment variables or configuration files to manage sensitive information securely.
| } | ||
| } | ||
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| public static Connection getConnection() throws SQLException { |
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It's a good practice to handle SQLException inside the getConnection method rather than throwing it, so you can provide more informative error messages and handle specific cases if necessary.
src/main/java/mate/academy/Main.java
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| public static void main(String[] args) { | ||
| BookDao bookDao = (BookDao) INJECTOR.getInstance(BookDao.class); | ||
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| // Initialize data |
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2, book.getPrice()); | ||
| statement.setLong(3, book.getId()); | ||
| statement.executeUpdate(); |
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should we check if rows were updated?
| .prepareStatement(query, Statement.RETURN_GENERATED_KEYS)) { | ||
| statement.setString(1, book.getTitle()); | ||
| statement.setBigDecimal(2, book.getPrice()); | ||
| statement.executeUpdate(); |
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should we check if rows were updated?
-added check if rows were updated
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