What is the output of the following code? int x = 10; try { x = x / 0; } catch(ArithmeticException e) { x = x + 5; } finally { x = x * 2; } System.out.println(x);

The correct answer is B: 30. ArithmeticException is caught, x becomes 10+5=15. Finally block executes, x becomes 15*2=30. Finally block always executes regardless of exception.

In Java, which method of Throwable class is used to obtain the cause of an exception?

The correct answer is B: getCause(). The getCause() method returns the cause (underlying Throwable) of this Throwable. It's useful for exception chaining.

What is the difference between update() and updateRow() methods in ResultSet?

The correct answer is A: update() modifies a single column, updateRow() commits all column changes. update*() methods (like updateInt(), updateString()) modify individual column values in the current row, while updateRow() commits all these changes to the database.

What is the difference between read() and read(byte[] b) methods in InputStream?

The correct answer is A: read() returns a byte, read(byte[] b) returns multiple bytes in an array. read() reads and returns a single byte as an int (0-255 or -1 for EOF). read(byte[] b) reads bytes into an array and returns the number of bytes read.

Which of the following statements about static methods is correct?

The correct answer is C: Static methods can only be called using the class name. Static methods belong to the class, not to any instance. They are called using the class name (e.g., ClassName.methodName()). They cannot directly access instance variables and cannot be overridden (though they can be hidden).

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Java Programming
JDBC

Java OOP, collections, multithreading

25 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–25 of 25

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.21 Hard JDBC

In JDBC, what does the ResultSet.TYPE_SCROLL_INSENSITIVE constant represent?

A Non-scrollable result set

B Scrollable result set that doesn't reflect database changes

C Forward-only result set

D Bidirectional result set

Correct Answer: B. Scrollable result set that doesn't reflect database changes

EXPLANATION

TYPE_SCROLL_INSENSITIVE creates scrollable ResultSet (can move forward/backward) but changes made to database after ResultSet creation are not reflected.

Test

Q.22 Hard JDBC

Which JDBC feature allows you to call stored procedures?

A Statement

B PreparedStatement

C CallableStatement

D ExecutableStatement

Correct Answer: C. CallableStatement

EXPLANATION

CallableStatement is used to invoke stored procedures and functions. It extends PreparedStatement and supports IN, OUT, and INOUT parameters.

Test

Q.23 Hard JDBC

What is the difference between execute(), executeQuery(), and executeUpdate()?

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

B All three are identical

C execute() is fastest, others are slower

D executeQuery() updates database, executeUpdate() retrieves data

Correct Answer: A. execute() returns boolean, executeQuery() returns ResultSet, executeUpdate() returns int

EXPLANATION

execute() returns boolean (true if ResultSet available), executeQuery() returns ResultSet for SELECT, executeUpdate() returns row count for INSERT/UPDATE/DELETE.

Test

Q.24 Hard JDBC

How would you implement batch processing in JDBC for multiple INSERT operations?

A Use addBatch() and executeBatch() methods

B Execute each insert in a loop separately

C Use multiple connections

D Create multiple statements

Correct Answer: A. Use addBatch() and executeBatch() methods

EXPLANATION

addBatch() adds SQL command to batch, executeBatch() executes all batched commands at once, improving performance significantly for multiple operations.

Test

Q.25 Hard JDBC

Consider code: String query = "SELECT * FROM users WHERE id=" + userId; stmt.executeQuery(query); What security issue exists?

A Performance degradation

B SQL Injection vulnerability

C Memory leak

D Connection timeout

Correct Answer: B. SQL Injection vulnerability

EXPLANATION

This is vulnerable to SQL injection as user input is directly concatenated. Using PreparedStatement with parameters prevents this: "SELECT * FROM users WHERE id=?"

Test

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