A RandomAccessFile is opened with mode 'r'. Which operation will throw an exception?

The correct answer is C: Writing bytes to the file. Mode 'r' allows read-only access. Write operations will throw IOException.

What is the return type of FileInputStream's read() method?

The correct answer is B: int. The read() method returns an int. It returns the byte value (0-255) or -1 if end of stream is reached. This is why it needs to be cast to byte if needed.

Which of the following correctly uses method reference with constructor?

The correct answer is A: String::new. Constructor method references use ClassName::new syntax. String::new refers to the String constructor and can be used wherever a Supplier is expected.

What is the output of this code? ExecutorService executor = Executors.newSingleThreadExecutor(); executor.submit(() -> System.out.println("Task 1")); executor.submit(() -> System.out.println("Task 2")); executor.shutdown();

The correct answer is B: Task 1 printed, then Task 2 printed. newSingleThreadExecutor() creates an executor with exactly one thread. Tasks are queued and executed sequentially in the order submitted. Task 1 will always execute before Task 2.

What is the type of the following lambda expression: x -> x.length()?

The correct answer is A: Function. Function takes one argument of type T and returns R. Here String -> Integer (length), so Function.

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Java Programming
Lambda Expressions

Java OOP, collections, multithreading

51 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 51–51 of 51

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.51 Medium Lambda Expressions

Which of the following lambda expressions is invalid?

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

B x -> x * 2

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

D -> x + y

Correct Answer: D. -> x + y

EXPLANATION

Lambda must have parameter list (even if empty with ()). Missing parameter list '() -> x + y' is invalid syntax.

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Java Programming Lambda Expressions

Java Programming
Lambda Expressions