What happens when @Lazy annotation is applied to a singleton bean in Spring?

The correct answer is A: The bean is created only when first accessed. @Lazy defers bean instantiation until it's first requested, overriding the default eager initialization behavior of singleton beans.

Which of the following correctly represents variable declaration and initialization in Java?

The correct answer is C: boolean flag = true;. Option C is correct. Option A causes a compilation error (cannot assign double to int). Option B works but there's implicit conversion. Option D causes a compilation error (cannot assign int to String).

Consider the following code snippet: public T processData(List

The correct answer is B: The list can contain elements that are subtypes of T. The wildcard '? extends T' means the list can contain any type that is a subtype of T. This allows reading from the list safely but restricts writing.

For processing delimited text files with variable field counts, which class is most suitable?

The correct answer is B: BufferedReader with custom parsing logic. BufferedReader combined with custom parsing logic (using split or regex) handles variable-length fields better than fixed-format alternatives.

In Spring Framework, what does the @Autowired annotation do when autowiring candidates are ambiguous?

The correct answer is D: Both B and C are correct. When multiple beans match the injection point, Spring throws an exception unless @Primary is used to indicate the preferred bean or @Qualifier specifies which bean to inject.

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Java Programming

Java OOP, collections, multithreading

476 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–40 of 476

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.31 Medium Spring Framework Basics

A Spring application requires constructor-based dependency injection for a mandatory dependency. Which approach is best?

A @Autowired on setter method

B @Autowired on constructor

C @Resource annotation

D Manual object creation

Correct Answer: B. @Autowired on constructor

EXPLANATION

Constructor-based DI ensures mandatory dependencies are provided at object creation time and is considered a best practice for required dependencies.

Test

Q.32 Medium Lambda Expressions

Consider the following code:
List fruits = Arrays.asList("apple", "banana", "cherry");
fruits.removeIf(s -> s.length() > 5);

What will be the contents of 'fruits' list after execution?

A ["apple", "banana", "cherry"]

B ["apple"]

C ["apple", "cherry"]

D []

Correct Answer: B. ["apple"]

EXPLANATION

removeIf() removes all elements that satisfy the lambda predicate. Strings with length > 5 are "banana" (6 chars) and "cherry" (6 chars). Only "apple" (5 chars) remains as its length is not greater than 5.

Test

Q.33 Medium Lambda Expressions

A stream processes a list of strings and applies a lambda to convert them to uppercase. Which intermediate operation should be used?

A filter(s -> s.toUpperCase())

B map(s -> s.toUpperCase())

C peek(s -> s.toUpperCase())

D collect(s -> s.toUpperCase())

Correct Answer: B. map(s -> s.toUpperCase())

EXPLANATION

The map() intermediate operation transforms each element using the provided lambda function. filter() returns boolean, peek() doesn't transform, and collect() is a terminal operation. map() is the correct choice for transformation.

Test

Q.34 Medium Lambda Expressions

Which of the following lambda expressions is INVALID in Java?

A () -> System.out.println("Hello")

B (int x) -> x * x

C (x, y) -> { return x + y; }

D (x, y) -> return x + y;

Correct Answer: D. (x, y) -> return x + y;

EXPLANATION

In a lambda expression, if the body uses curly braces, 'return' keyword is required. But without curly braces, 'return' keyword cannot be used. Option D is invalid because it has 'return' without curly braces.

Test

Q.35 Medium Lambda Expressions

Which stream operation uses a lambda expression to transform elements from one type to another?

A filter()

B map()

C forEach()

D reduce()

Correct Answer: B. map()

EXPLANATION

map() is used to transform elements. It takes a Function lambda that converts each element from one type/value to another.

Test

Q.36 Medium Lambda Expressions

Which of the following correctly uses a method reference as an alternative to a lambda expression?

A System.out::println instead of (x) -> System.out.println(x)

B String::length instead of (s) -> s.length()

C Integer::parseInt instead of (s) -> Integer.parseInt(s)

D All of the above

Correct Answer: D. All of the above

EXPLANATION

All three are valid method references that can replace their equivalent lambda expressions. Method references are a shorthand notation introduced in Java 8.

Test

Q.37 Medium Lambda Expressions

Consider: Comparator comp = (a, b) -> b - a; List list = Arrays.asList(3,1,2); Collections.sort(list, comp); What is the result?

A [1, 2, 3]

B [3, 2, 1]

C [2, 1, 3]

D [1, 3, 2]

Correct Answer: B. [3, 2, 1]

EXPLANATION

The comparator (a, b) -> b - a returns negative values when b < a, causing elements to be sorted in descending order. Result is [3, 2, 1].

Test

Q.38 Medium Lambda Expressions

Which lambda expression correctly implements a custom functional interface: public interface Math { int calculate(int a, int b); }

A (a, b) -> a + b

B () -> 0

C (int a, int b) -> a - b

D Both A and C

Correct Answer: D. Both A and C

EXPLANATION

Both expressions are valid. Option A uses type inference while Option C explicitly specifies types. Both can implement the calculate method.

Test

Q.39 Medium Lambda Expressions

What is the output of: List nums = Arrays.asList(1,2,3); nums.stream().filter(x -> x > 1).forEach(System.out::println);

A 1 2 3

B 2 3

C 1

D Nothing is printed

Correct Answer: B. 2 3

EXPLANATION

filter(x -> x > 1) keeps only elements greater than 1, which are 2 and 3. These are then printed on separate lines using forEach.

Test

Q.40 Medium Lambda Expressions

Consider the code: List names = Arrays.asList("Alice", "Bob"); names.forEach(name -> System.out.println(name)); What type of functional interface is used in forEach?

A Function

B Consumer

C Supplier

D Predicate

Correct Answer: B. Consumer

EXPLANATION

forEach accepts a Consumer functional interface. Consumer<T> takes an input and performs an action without returning anything, which matches the System.out.println action.

Test

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