Assertions Questions with Answers | Java Programming MCQ | Page 4

Assertions questions with answers in Java programming test a candidate’s ability to debug and validate logic efficiently. The assert keyword is used to verify assumptions during program execution, ensuring code reliability and preventing logical errors. Many placement tests from companies like TCS, Infosys, and Wipro include Java Assertion MCQs to evaluate coding fundamentals. This section offers a collection of Java programming questions and answers with explanations to help you understand the use, syntax, and runtime behavior of assertions. Practice these questions to strengthen your programming logic and prepare effectively for technical interviews and coding tests.

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Q31

What is the two-form syntax of assert statement?

A Simple and complex
B Basic and advanced
C With and without message
D Conditional and unconditional

Answer: Option C

Explanation: Assert can have just a boolean expression or boolean expression followed by a message.

Q32

When should assertions typically be used?

A For validating user input
B For checking method arguments in public methods
C For internal invariants and debugging
D For handling file I/O errors

Answer: Option C

Explanation: Assertions are for internal invariants and should not replace regular error handling.

Q33

Which of these is NOT a valid use of assertions?

A Checking internal class invariants
B Validating input parameters in private methods
C Checking method arguments in public methods
D Verifying postconditions after method execution

Answer: Option C

Explanation: Assertions should not be used for argument checking in public methods.

Q34

What happens if assertions are disabled?

A They throw exceptions
B They are evaluated but ignored
C They have no effect
D They cause compilation warnings

Answer: Option C

Explanation: When disabled, assert statements have no effect and are essentially skipped.

Q35

Which command enables assertions for all classes except those in com.example package?

A -ea -da:com.example...
B -ea:* -da:com.example...
C -ea:-com.example...
D -enable -disable:com.example...

Answer: Option C

Explanation: The -ea:-com.example... syntax disables assertions for specific packages.

Q36

What type of exception is thrown when an assertion fails?

A AssertionException
B RuntimeException
C AssertionError
D AssertFailure

Answer: Option C

Explanation: AssertionError extends Error, not Exception.

Q37

Which of these is a correct assertion statement with message?

A assert condition : "message";
B assert condition "message";
C assert ("message") condition;
D assert : condition "message";

Answer: Option A

Explanation: The message follows the boolean expression after a colon.

Q38

Why should assertions not have side effects?

A They make code run slower
B They can cause different behavior when assertions are disabled
C They are illegal in Java
D They improve performance

Answer: Option B

Explanation: Since assertions can be disabled, side effects would create inconsistent behavior.

Q39

What is the default state of assertions when running a Java program?

A Enabled for all classes
B Disabled for all classes
C Enabled only for system classes
D Enabled only for user classes

Answer: Option B

Explanation: Assertions are disabled by default for backward compatibility.

Q40

Which package contains the AssertionError class?

A java.util
B java.lang
C java.assert
D java.error

Answer: Option B

Explanation: AssertionError is in java.lang package like other fundamental classes.

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