When using JDBC with Spring Framework in 2024-25, which approach is recommended for resource management?
A
Manual try-catch blocks
B
Try-with-resources statement
C
JdbcTemplate with Spring
D
DriverManager only
Correct Answer:
C. JdbcTemplate with Spring
JdbcTemplate in Spring Framework automatically manages JDBC resources and is the recommended approach in modern applications.
In JDBC, what is the significance of setting FetchSize on a Statement when dealing with large ResultSets?
A
It determines the maximum number of rows to fetch from database in one round-trip
B
It sets the total memory allocated for ResultSet
C
It automatically closes the ResultSet
D
It enables caching of all rows in memory
Correct Answer:
A. It determines the maximum number of rows to fetch from database in one round-trip
FetchSize controls how many rows are fetched from the database at once, optimizing performance for large datasets.
Which JDBC feature should be used for executing multiple SQL statements in a batch for optimal performance?
A
executeUpdate() in a loop
B
executeBatch() with addBatch()
C
execute() method
D
Multiple Statement objects
Correct Answer:
B. executeBatch() with addBatch()
executeBatch() with addBatch() reduces network round-trips and improves performance for bulk operations.
In a JDBC application, when using transactions with setAutoCommit(false), what happens to intermediate savepoints if rollback() is called?
A
All changes are saved
B
Only savepoint changes are rolled back
C
All changes since last commit are rolled back
D
The entire connection is closed
Correct Answer:
C. All changes since last commit are rolled back
When rollback() is called without savepoints, all changes made since the last commit are undone and rolled back.
Consider a scenario: A developer uses Statement with user input directly in SQL queries. What is the primary risk?
A
Slower query execution
B
SQL Injection attacks
C
Memory leaks
D
Connection timeout
Correct Answer:
B. SQL Injection attacks
Direct concatenation of user input in SQL queries exposes the application to SQL injection attacks. PreparedStatement should be used instead.
In a multi-threaded JDBC application, why should each thread have its own Connection object?
A
To improve database performance
B
Connections are not thread-safe and sharing causes race conditions
C
To reduce memory usage
D
It is just a best practice with no technical requirement
Correct Answer:
B. Connections are not thread-safe and sharing causes race conditions
JDBC Connections are not thread-safe. Each thread must have its own Connection to prevent concurrent access issues and data corruption.
What is the optimal approach to handle JDBC resources to prevent memory leaks in a production application?
A
Use try-catch blocks and manually close resources
B
Rely on garbage collection to close resources
C
Use try-with-resources statement to auto-close resources
D
Create resources globally and close them at application shutdown
Correct Answer:
C. Use try-with-resources statement to auto-close resources
Try-with-resources (try-with-resources statement) automatically closes AutoCloseable resources, preventing memory leaks.
Consider a scenario where a developer retrieves a ResultSet and then closes the Statement object. What happens to the ResultSet?
A
The ResultSet remains valid and can still be accessed
B
The ResultSet becomes invalid in most drivers (implementation-dependent)
C
An immediate SQLException is thrown
D
The database automatically commits pending changes
Correct Answer:
B. The ResultSet becomes invalid in most drivers (implementation-dependent)
Closing a Statement typically invalidates its associated ResultSet in most JDBC drivers, though behavior may vary.
A developer creates a JDBC connection but forgets to close it. What might be the consequence?
A
Automatic garbage collection will close it immediately
B
Resource leak leading to exhaustion of database connections
C
The program will automatically rollback all transactions
D
No impact as JDBC handles it automatically
Correct Answer:
B. Resource leak leading to exhaustion of database connections
Unclosed connections remain allocated, eventually exhausting the connection pool and causing application failures.
In JDBC, what is the purpose of using a SavePoint in a transaction?
A
To save the current connection state
B
To create a checkpoint within a transaction that can be rolled back to independently
C
To automatically commit pending changes
D
To lock the database for exclusive access
Correct Answer:
B. To create a checkpoint within a transaction that can be rolled back to independently
A SavePoint allows you to roll back part of a transaction without rolling back the entire transaction. You can create nested transactions by setting multiple savepoints and rolling back to specific ones.
