What is the primary purpose of transient keyword in Java serialization?

The correct answer is B: Exclude specific fields from serialization. The transient keyword marks fields that should not be serialized, useful for excluding sensitive data or non-serializable objects.

What will be the output? class Test { int x = 5; { x = 10; } Test() { x = 15; } public static void main(String[] args) { Test t = new Test(); System.out.println(t.x); } }

The correct answer is C: 15. Instance initializer block executes after variable initialization but before constructor. Constructor executes last, setting x = 15.

Which of the following lambda expressions is INCORRECT?

The correct answer is C: (int x, int y) -> x + y. In option C, you cannot specify types in lambda parameters when using implicit typing. It should be either (x, y) or explicitly define all parameters.

What is the PECS principle in Java Generics?

The correct answer is B: Producer Extends, Consumer Super. PECS (Producer Extends, Consumer Super) is a guideline: use 'extends' for producers (reading) and 'super' for consumers (writing).

What is the output of this code? Consumer print = s -> System.out.println(s.toUpperCase()); print.accept("java");

The correct answer is B: JAVA. Consumer accepts one argument and returns nothing. print.accept("java") calls lambda which prints s.toUpperCase() = "JAVA".

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Java Programming

Java OOP, collections, multithreading

212 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 211–212 of 212

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.211 Hard Basics & Syntax

What will be printed? System.out.println(10 + 20 + "Java");

A 30Java

B 10 + 20 + Java

C 1020Java

D Compilation error

Correct Answer: A. 30Java

EXPLANATION

String concatenation works left to right. 10 + 20 = 30 (integer addition), then 30 + "Java" = "30Java" (string concatenation).

Test

Q.212 Hard Basics & Syntax

Consider the code: int a = 5; int b = a++; System.out.println(a + " " + b); What is the output?

A 5 5

B 6 5

C 5 6

D 6 6

Correct Answer: B. 6 5

EXPLANATION

The post-increment operator (a++) returns the value before incrementing. So b = 5, then a becomes 6. Output: 6 5

Test

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