What approaches exist for integrating a Java application with a database?

There are several main approaches to integrating a Java application with a database:

1. JDBC (Java Database Connectivity) — a basic API for connecting and executing SQL queries to a database. It allows direct work with SQL but requires a lot of boilerplate code.

2. ORM frameworks (e.g., Hibernate, JPA) — abstract the database work, allowing you to work with Java objects rather than SQL directly. They automate query generation, transaction management, and caching.

3. Spring Data — a layer over ORM and JDBC that simplifies creating repositories and data access through interfaces and method names that reflect queries.

4. MyBatis — a framework that combines SQL and an object-oriented approach, allowing manual SQL writing but managing result mapping to objects.

5. JPA (Java Persistence API) — a standard specification for ORM in Java, implemented by Hibernate, EclipseLink, and others.

Example of a simple connection using JDBC:

Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM users");
while (rs.next()) {
    System.out.println(rs.getString("username"));
}
rs.close();
stmt.close();
conn.close();

The choice of approach depends on project requirements, complexity, and team preferences.