Hibernate provides two primary methods for retrieving objects from a database: session.get() and session.load(). These methods differ significantly in their loading behavior and performance characteristics.

Load Method Behavior

The load() method employs lazy loading. When envoked, it returns a proxy object containing only the entity's ID. No SQL query is executed at this stage. The actual database query occurs only when accessing non-ID properties of the object.

Session session = HibernateUtil.openSession();
User user = (User)session.load(User.class, 2);
System.out.println(user.getId()); // No SQL executed
System.out.println(user.getUsername()); // Triggers SQL query

Output:

2
Hibernate: select user0_.id as id0_0_, user0_.username as username0_0_ from user user0_ where user0_.id=?
username_value

Get Method Behavior

The get() method uses eager loading. It immediately executes an SQL query to retrieve the complete object, regardless of whether its properties are accessed.

Session session = HibernateUtil.openSession();
User user = (User)session.get(User.class, 2); // SQL executed immediately

Output:

Hibernate: select user0_.id as id0_0_, user0_.username as username0_0_ from user user0_ where user0_.id=?

Error Handling Differences

1. Non-existent ID with get(): Throws NullPointerException

User user = (User)session.get(User.class, 20);
System.out.println(user.getUsername()); // NullPointerException

2. Non-existent ID with load(): Throws ObjectNotFoundException

User user = (User)session.load(User.class, 20);
System.out.println(user.getUsername()); // ObjectNotFoundException

3. LazyInitializationException: Occurs when accessing a lazily-loaded object after session closure

public User loadUser(int id) {
    Session session = HibernateUtil.openSession();
    User user = (User)session.load(User.class, id);
    session.close();
    return user; // Problematic - session closed before access
}

Performance Considerations

• load() is more efficient for scenarios where object properties might not be needed
• get() is simpler but always incurs databsae access overhead
• Choose based on your specific use case and object access patterns