Which statement correctly defines a generic class with multiple type parameters and bounds?

The correct answer is C: class Container { }. Multiple type parameters with bounds must be comma-separated and each can have its own upper bound. Option C shows correct syntax with recursive bound on T and bound on K.

When processing a large XML file, which approach is most memory-efficient?

The correct answer is C: Use SAX parser or streaming XML parser. SAX parsers and streaming XML parsers process XML sequentially without loading the entire document, making them ideal for large files.

Consider the following code. What will be the likely behavior? java synchronized void method1() { method2(); } synchronized void method2() { }

The correct answer is C: Code will execute without issues due to reentrant locks. Java's intrinsic locks are reentrant, meaning the same thread can acquire the same lock multiple times. The thread can call method2() from method1() without deadlock.

Which of the following collections maintains insertion order while allowing fast random access?

The correct answer is A: ArrayList. ArrayList maintains insertion order and provides O(1) random access via index. LinkedHashMap maintains insertion order but is a Map, not a List.

Which of the following will throw a NullPointerException? String s = null; System.out.println(s.length());

The correct answer is C: s.length(). Calling a method on a null reference throws NullPointerException. s.length() tries to invoke method on null, causing the exception.

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Java Programming
JDBC

Java OOP, collections, multithreading

46 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–20 of 46

Topics in Java Programming

All Basics & Syntax 100 OOP in Java 100 Collections Framework 100 Multithreading 100 Exception Handling 100 I/O Streams 100 JDBC 100 Generics 100 Lambda Expressions 100 Spring Framework Basics 58

Q.11 Medium JDBC

What is the purpose of Connection pooling in JDBC applications?

A To store query results temporarily

B To reuse database connections instead of creating new ones each time

C To encrypt database connections

D To monitor database performance

Correct Answer: B. To reuse database connections instead of creating new ones each time

EXPLANATION

Connection pooling maintains a pool of reusable connections, reducing the overhead of creating new connections for each request, improving application performance.

Test

Q.12 Medium JDBC

A developer needs to execute a query that returns multiple result sets. Which Statement type should be used?

A Statement with executeQuery()

B PreparedStatement with setFetchSize()

C Statement with execute() or PreparedStatement with execute()

D CallableStatement only

Correct Answer: C. Statement with execute() or PreparedStatement with execute()

EXPLANATION

The execute() method returns a boolean and can handle multiple result sets via getResultSet(), getUpdateCount(), and getMoreResults() methods.

Test

Q.13 Medium JDBC

Which JDBC driver type is considered the most portable across different databases?

A Type 1 - JDBC-ODBC Bridge

B Type 2 - Native API Driver

C Type 3 - Network Protocol Driver

D Type 4 - Thin Driver

Correct Answer: D. Type 4 - Thin Driver

EXPLANATION

Type 4 drivers are pure Java implementations that directly communicate with the database, making them platform-independent and most portable.

Test

Q.14 Medium JDBC

What happens if you call next() on a ResultSet after the last row?

A Throws SQLException

B Returns false

C Returns true

D Throws NoSuchElementException

Correct Answer: B. Returns false

EXPLANATION

next() returns false when the cursor is positioned beyond the last row, indicating no more rows available.

Test

Q.15 Medium JDBC

Which statement should be used when you need to retrieve column information without executing multiple queries?

A Statement with multiple executeQuery()

B PreparedStatement

C ResultSetMetaData

D DatabaseMetaData

Correct Answer: C. ResultSetMetaData

EXPLANATION

ResultSetMetaData provides column information directly from the ResultSet without additional queries.

Test

Q.16 Medium JDBC

What is the difference between execute() and executeUpdate() methods?

A execute() returns boolean, executeUpdate() returns int

B execute() can execute any SQL statement, executeUpdate() only for DML

C Both A and B are correct

D There is no difference

Correct Answer: C. Both A and B are correct

EXPLANATION

execute() returns true/false and handles any SQL, while executeUpdate() returns affected rows count for DML statements only.

Test

Q.17 Medium JDBC

In JDBC, which class is used to retrieve database metadata information?

A ResultSet

B Statement

C DatabaseMetaData

D Connection

Correct Answer: C. DatabaseMetaData

EXPLANATION

DatabaseMetaData provides information about the database, tables, columns, and other database properties.

Test

Q.18 Medium JDBC

What does ResultSetMetaData.getColumnCount() return?

A Number of rows in ResultSet

B Number of columns in ResultSet

C Column data type

D Column name

Correct Answer: B. Number of columns in ResultSet

EXPLANATION

getColumnCount() returns the total number of columns present in the ResultSet.

Test

Q.19 Medium JDBC

What is the benefit of using PreparedStatement over Statement for repeated queries?

A Faster execution due to pre-compilation

B Automatic SQL injection prevention

C Better readability of code

D Both A and B

Correct Answer: D. Both A and B

EXPLANATION

PreparedStatement offers both pre-compilation for performance and SQL injection prevention through parameterized queries.

Test

Q.20 Medium JDBC

Which JDBC method executes UPDATE, INSERT, or DELETE statements?

A executeQuery()

B execute()

C executeUpdate()

D executeBatch()

Correct Answer: C. executeUpdate()

EXPLANATION

executeUpdate() executes DML statements and returns the number of rows affected.

Test

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