Programming Practices (CS-406) - Important Questions

Write a Java program demonstrating thread creation using both a Thread subclass and a Runnable implementation. Start multiple threads, use join to wait for their completion, and ensure synchronized access to a shared counter so that final count is correct. Explain the thread lifecycle and illustrate the state transitions observed during your program execution.

Explain the Java thread lifecycle in detail. Describe each state (New, Runnable, Blocked/Waiting, Timed Waiting, Terminated), the events or API calls that cause transitions between states, and provide short code snippets that illustrate typical transitions.

Discuss synchronization mechanisms in Java. Explain synchronized methods and synchronized blocks, the concept of intrinsic locks (monitor), and the ReentrantLock class. Define deadlock and list strategies to prevent or recover from deadlocks. Support your answer with concise code examples.

Explain inter-thread communication using wait(), notify(), and notifyAll(). Provide a producer-consumer example using a bounded buffer that employs wait/notify for coordination. Also discuss higher-level alternatives using java.util.concurrent classes (for example, BlockingQueue) and when they are preferred.

Describe the Java concurrency utilities related to task execution: Executor framework, ThreadPoolExecutor, Callable and Future, and ScheduledExecutorService. Write code to submit tasks to a fixed thread pool and retrieve results using Future.

Write JDBC code to connect to a MySQL or Oracle database and perform Create, Read, Update and Delete (CRUD) operations using PreparedStatement. Demonstrate proper exception handling and resource management using try-with-resources, and explain why PreparedStatement is preferred over Statement for parameterized queries.

Explain the JDBC architecture and the role of JDBC drivers. Compare DriverManager and DataSource approaches for obtaining connections. Describe Statement, PreparedStatement and CallableStatement and list their advantages and typical use-cases.

Discuss transaction management in JDBC: auto-commit mode, explicit commit and rollback, use of savepoints, and common transaction isolation levels. Provide JDBC code that demonstrates disabling auto-commit, executing multiple statements within a transaction, and rolling back on error.

Describe ResultSet types and concurrency modes in JDBC: TYPE_FORWARD_ONLY, TYPE_SCROLL_INSENSITIVE, TYPE_SCROLL_SENSITIVE and CONCUR_READ_ONLY, CONCUR_UPDATABLE. Explain how to perform batch updates and how to retrieve auto-generated keys after an INSERT.

Explain the purpose of connection pooling and how it improves database application performance. Demonstrate, at a high level, how to configure and use a DataSource-based connection pool (for example, HikariCP or Apache DBCP) in a Java application.