Which exception is thrown when you try to serialize an object that contains non-serializable fields?

The correct answer is B: NotSerializableException. NotSerializableException is thrown when attempting to serialize an object whose class does not implement Serializable or contains non-serializable fields.

In Java NIO, which class replaces traditional Stream-based I/O for better performance?

The correct answer is B: ByteBuffer and Channels. Java NIO (New I/O) uses ByteBuffer and Channels for non-blocking, scalable I/O operations with better performance than traditional streams.

In Java, a class can implement multiple interfaces but can extend only one class. This design choice primarily supports which principle?

The correct answer is C: Avoiding diamond problem in single inheritance. Multiple inheritance of implementation can cause the diamond problem. Java avoids this by allowing single class inheritance but multiple interface implementation.

In Java 2024, if you need a collection that automatically removes entries based on garbage collection patterns, which would you choose?

The correct answer is A: WeakHashMap. WeakHashMap uses weak references for keys. When a key is no longer referenced elsewhere, it becomes eligible for garbage collection and is automatically removed from the map.

Which annotation is used to provide external configuration properties to Spring beans in the 2024 Spring Boot version?

The correct answer is D: All of the above. @PropertySource loads properties from files, @ConfigurationProperties binds properties to bean properties, and @Value injects individual values. All are used for configuration.

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Java Programming
I/O Streams

Java OOP, collections, multithreading

27 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–27 of 27

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.21 Easy I/O Streams

Which of the following correctly demonstrates chaining multiple filters in Java I/O?

A new BufferedReader(new FileReader(file))

B new FileReader(new BufferedReader(file))

C new Reader(new BufferedReader(new FileReader(file)))

D new BufferedInputStream(new FileInputStream(new File(file)))

Correct Answer: A. new BufferedReader(new FileReader(file))

EXPLANATION

Filter streams are chained from inside-out. FileReader is wrapped with BufferedReader for better performance.

Test

Q.22 Easy I/O Streams

Which method reads a complete line from a BufferedReader?

A read()

B readLine()

C readString()

D nextLine()

Correct Answer: B. readLine()

EXPLANATION

The readLine() method reads a line of text from the BufferedReader, returning a String without the newline character, or null if end of stream is reached.

Test

Q.23 Easy I/O Streams

What exception is thrown when a file is not found while creating FileInputStream?

A NullPointerException

B FileNotFoundException

C IOException

D StreamException

Correct Answer: B. FileNotFoundException

EXPLANATION

FileNotFoundException (a subclass of IOException) is thrown when the specified file does not exist or cannot be opened.

Test

Q.24 Easy I/O Streams

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

A byte

B int

C char

D void

Correct Answer: B. int

EXPLANATION

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.

Test

Q.25 Easy I/O Streams

What is the purpose of the flush() method in output streams?

A Close the stream

B Clear the buffer and write pending data to the underlying stream

C Reset the stream position

D Release memory allocated to the stream

Correct Answer: B. Clear the buffer and write pending data to the underlying stream

EXPLANATION

The flush() method forces any buffered output to be written to the underlying stream immediately without closing it.

Test

Q.26 Easy I/O Streams

Which method is used to read a single byte from a FileInputStream?

A read()

B readByte()

C readSingleByte()

D nextByte()

Correct Answer: A. read()

EXPLANATION

The read() method reads a single byte and returns it as an integer. Returns -1 if end of stream is reached.

Test

Q.27 Easy I/O Streams

Which of the following is a character stream class in Java?

A FileReader

B FileInputStream

C DataInputStream

D BufferedInputStream

Correct Answer: A. FileReader

EXPLANATION

FileReader is a character stream class that reads characters from a file. FileInputStream, DataInputStream, and BufferedInputStream are byte stream classes.

Test

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