What is the output of:
BiFunction<Integer, Integer, Integer> add = (a, b) -> a + b;
System.out.println(add.apply(5, 3));
Answer: A
BiFunction takes two Integer parameters and returns their sum. apply(5, 3) returns 5 + 3 = 8.
Q.242Easy
What is the result of this code?
UnaryOperator<Integer> square = x -> x * x;
System.out.println(square.apply(5));
Answer: A
UnaryOperator applies the operation x * x where x = 5, resulting in 25.
Q.243Easy
Which of the following best describes a functional interface?
Answer: B
A functional interface must have exactly one abstract method, which can be implemented using lambda expressions.
Q.244Easy
What will be the output of:
Supplier<String> greeting = () -> "Hello";
System.out.println(greeting.get());
Answer: A
Supplier.get() returns the value produced by the lambda expression, which is "Hello".
Q.245Easy
Which of the following is a valid functional interface that can be used with lambda expressions?
Answer: A
A functional interface must have exactly one abstract method. This is the defining characteristic that allows it to be used with lambda expressions and method references.
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Q.246Easy
Which annotation is used to mark an interface as a functional interface in Java?
Answer: B
@FunctionalInterface is the standard annotation introduced in Java 8 to explicitly mark an interface as a functional interface. It helps in compile-time checking.
Q.247Easy
Which of the following lambda expressions is syntactically incorrect?
Answer: C
The syntax (x, y,) is incorrect because there's a trailing comma after y. The correct syntax would be (x, y) -> x + y.
Q.248Easy
What is the purpose of a Predicate functional interface in Java?
Answer: C
Predicate<T> is a functional interface that takes a single input of type T and returns a boolean. It's commonly used for filtering operations in streams.
Q.249Easy
In a lambda expression, what does the arrow (->) operator represent?
Answer: B
The arrow (->) in lambda expressions separates the parameter list on the left from the method body on the right. It's a syntax element specific to lambda expressions.
Q.250Easy
What is the correct syntax for a lambda expression with no parameters that returns a fixed value?
Answer: B
When a lambda has no parameters, empty parentheses () are required before the arrow. Options A and D are syntactically incorrect.
Q.251Easy
Given: Function<Integer, Integer> f = x -> x * 2; Integer result = f.apply(5); What is the value of result?
Answer: B
The lambda expression x -> x * 2 multiplies the input by 2. When applied to 5, it returns 10.
Q.252Easy
Which functional interface is used to create a lambda expression that takes two integers and returns a boolean value?
Answer: A
BiPredicate<T, U> is a functional interface that takes two parameters and returns a boolean. This matches the requirement of taking two integers and returning a boolean value.
Q.253Easy
What will be the output of the following code?
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
numbers.stream().filter(n -> n % 2 == 0).forEach(System.out::println);
Answer: B
The filter operation with lambda expression (n -> n % 2 == 0) filters even numbers only. So 2 and 4 are printed, each on a new line due to println.
Q.254Easy
Which annotation is used to mark a class as a Spring Bean in the latest Spring Framework?
Answer: B
@Component is a generic stereotype annotation for any Spring-managed component. @Bean is used on methods, while @Service and @Controller are specialized versions of @Component.
Q.255Easy
What is the primary purpose of Dependency Injection (DI) in Spring Framework?
Answer: B
DI reduces coupling by injecting dependencies rather than creating them internally, making code more testable and maintainable.
Q.256Easy
Which of the following is NOT a valid Spring bean scope in Spring 5.x+?
Answer: D
Valid scopes are singleton, prototype, request, session, application, and websocket. 'eternal' is not a valid scope.
Q.257Easy
What does @Autowired annotation do in Spring?
Answer: A
@Autowired performs type-based dependency injection. Spring looks for a bean of the required type and injects it automatically.
Q.258Easy
Which XML element is used to define a bean in Spring XML configuration?
Answer: B
The <bean> element is the standard XML element used in applicationContext.xml to define Spring beans.
Q.259Easy
In Spring Framework, what is the primary purpose of the @Autowired annotation?
Answer: A
@Autowired is used for dependency injection, allowing Spring to automatically resolve and inject bean dependencies without explicit configuration.
Q.260Easy
Which of the following correctly describes the lifecycle of a singleton-scoped Spring bean?
Answer: B
Singleton beans are instantiated once per Spring container and reused for the application's lifetime, making them memory-efficient for stateless objects.
