Java Programming

What is a key advantage of using lambda expressions in Java? a) Improved performance b) Simplified syntax and more readable code c) Better compatibility with older versions of Java d) Enhanced security Answer: b) Simplified syntax and more readable code Explanation: A key advantage of using lambda expressions in Java is the simplified syntax and […]

Which of the following is a common use case for lambda expressions in Java? a) To replace complex nested loops b) To implement algorithms c) To pass behavior as a parameter to methods d) To define custom data structures Answer: c) To pass behavior as a parameter to methods Explanation: One of the common use

Can lambda expressions be used with custom functional interfaces? a) No, lambda expressions can only be used with built-in functional interfaces b) Yes, but only with interfaces that extend built-in ones c) Yes, they can be used with any functional interface d) No, lambda expressions are limited to standard library interfaces Answer: c) Yes, they

Which of the following interfaces is NOT a functional interface in Java? a) Runnable b) Callable c) Comparator d) Iterable Answer: d) Iterable Explanation: The Iterable interface is not a functional interface in Java because it has more than one abstract method. A functional interface is defined as an interface that has exactly one abstract

Can lambda expressions be used in collections in Java? a) No, lambda expressions cannot be used in collections b) Yes, but only in Map collections c) Yes, they can be used with any collection d) Yes, but only in List collections Answer: c) Yes, they can be used with any collection Explanation: Lambda expressions can

What is the use of the Supplier functional interface in Java? a) To accept a single argument and return no result b) To return a result without taking any arguments c) To accept two arguments and return a result d) To filter elements based on a condition Answer: b) To return a result without taking

Which of the following is a valid method reference in Java? a) String::length b) System.out::println c) Math::max d) All of the above Answer: d) All of the above Explanation: All of the provided examples are valid method references in Java. Each one refers to a method using the :: syntax: String::length: Refers to the length

Which symbol is used to define a method reference in Java? a) -> b) :: c) => d) @ Answer: b) :: Explanation: The :: symbol is used to define a method reference in Java. This symbol allows you to refer to methods by their names, making it easier to pass methods as arguments to

What is method reference in Java? a) A way to refer to methods of a class or object b) A way to create a lambda expression c) A way to call a method without arguments d) A way to store a method in a variable Answer: a) A way to refer to methods of a

What is the purpose of the Optional class in Java? a) To represent the presence or absence of a value b) To create a lambda expression c) To throw exceptions d) To create collections Answer: a) To represent the presence or absence of a value Explanation: The Optional class in Java is used to represent

Can lambda expressions in Java access local variables? a) Yes, they can modify local variables b) No, they cannot access local variables c) Yes, but the local variables must be effectively final d) Yes, they can access and modify local variables Answer: c) Yes, but the local variables must be effectively final Explanation: Lambda expressions

Which functional interface in Java returns a boolean value? a) Function b) Predicate c) Consumer d) Supplier Answer: b) Predicate Explanation: The Predicate functional interface in Java is used to evaluate a condition and returns a boolean value. It is typically used in situations where a decision needs to be made based on a condition,

Can a lambda expression in Java have a body with multiple statements? a) No, it can only have a single statement b) Yes, if the statements are enclosed in curly braces c) Yes, but it cannot have a return statement d) No, it must be a single-line expression Answer: b) Yes, if the statements are

Which interface in Java is a marker interface for lambda expressions? a) Serializable b) FunctionalInterface c) Runnable d) Callable Answer: b) FunctionalInterface Explanation: The FunctionalInterface annotation in Java is a marker interface that indicates that an interface is intended to be a functional interface, meaning it has exactly one abstract method. This annotation helps to

What is the difference between a lambda expression and an anonymous class in Java? a) Lambda expressions can be used with any interface b) Anonymous classes are more efficient than lambda expressions c) Lambda expressions are more concise than anonymous classes d) There is no difference between the two Answer: c) Lambda expressions are more

Which functional interface in Java takes two arguments and returns a result? a) Function b) BiFunction c) Consumer d) Predicate Answer: b) BiFunction Explanation: The BiFunction functional interface in Java is used to represent a function that takes two arguments and returns a result. It is similar to the Function interface but operates on two

Can lambda expressions be used to create threads in Java? a) Yes, using the Runnable interface b) Yes, using the Callable interface c) No, lambda expressions cannot be used to create threads d) Yes, using the Supplier interface Answer: a) Yes, using the Runnable interface Explanation: Lambda expressions can be used to create threads in

What is the return type of a lambda expression in Java? a) The return type must be void b) The return type is inferred from the context c) The return type must be an object d) The return type must be a primitive type Answer: b) The return type is inferred from the context Explanation:

Which functional interface in Java does not return a result? a) Supplier b) Function c) Consumer d) Predicate Answer: c) Consumer Explanation: The Consumer functional interface in Java represents an operation that takes a single argument and returns no result. It is typically used for operations that consume a value but do not produce a

Can a lambda expression have more than one parameter? a) Yes, but only two parameters b) Yes, it can have multiple parameters c) No, it can only have one parameter d) No, it cannot have any parameters Answer: b) Yes, it can have multiple parameters Explanation: A lambda expression in Java can have multiple parameters.

Which of the following is a valid lambda expression in Java? a) (x) -> x * 2 b) x -> return x * 2; c) (x) -> {return x * 2;} d) All of the above Answer: d) All of the above Explanation: All of the provided options are valid lambda expressions in Java. Each

Which functional interface is commonly used with lambda expressions in Java? a) Runnable b) Callable c) Function d) Serializable Answer: c) Function Explanation: The Function interface is one of the most commonly used functional interfaces with lambda expressions in Java. It represents a function that takes a single argument and returns a result. The Function

What is the syntax for a basic lambda expression in Java? a) (parameters) -> expression b) (expression) -> parameters c) {expression} -> parameters d) (parameters) => expression Answer: a) (parameters) -> expression Explanation: The basic syntax for a lambda expression in Java is (parameters) -> expression. This syntax is straightforward: the parameters are enclosed in

Which Java version introduced lambda expressions? a) Java 6 b) Java 7 c) Java 8 d) Java 9 Answer: c) Java 8 Explanation: Lambda expressions were introduced in Java 8 as part of the significant enhancements to the language. This release marked a major shift towards functional programming, making Java more powerful and expressive. With

What is a lambda expression in Java? a) A way to define anonymous methods b) A method with no return type c) A way to write a single line of code d) A class that implements an interface Answer: a) A way to define anonymous methods Explanation: A lambda expression in Java is a concise