Which collection implementation is best for frequent insertions and deletions at both ends?

The correct answer is B: LinkedList. LinkedList provides O(1) operations for adding/removing at both ends via addFirst(), addLast(), removeFirst(), removeLast().

What will be the output of: System.out.println(Math.max(5, 10) - Math.min(3, 8));

The correct answer is C: 7. Math.max(5, 10) = 10, Math.min(3, 8) = 3. So 10 - 3 = 7.

What does the getSuppressed() method of Throwable class return in context of try-with-resources?

The correct answer is B: Array of exceptions suppressed while closing resources. When try-with-resources encounters an exception while closing a resource, it's added to the suppressed exceptions list. If an exception was already thrown in try, the close exception is suppressed rather than replacing it. getSuppressed() returns array of these suppressed exceptions.

Which annotation is used to mark a class as a Spring Bean in the latest Spring Framework?

The correct answer is B: @Component. @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.

What will happen if a finally block contains a return statement?

The correct answer is A: It will override any return from try or catch block. Return in finally block overrides returns in try or catch blocks. The finally return value is what gets returned.

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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 11–20 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.11 Easy I/O Streams

What is the output of the following code?
FileReader fr = new FileReader("test.txt");
int data = fr.read();
System.out.println(data);

A Character from the file

B ASCII value of the character

C -1 if EOF is reached

D File not found exception

Correct Answer: B. ASCII value of the character

EXPLANATION

FileReader.read() returns the ASCII/Unicode value of the character as an integer, not the character itself. It returns -1 when EOF is reached.

Test

Q.12 Easy I/O Streams

Which class in Java is used to read primitive data types from a binary stream?

A DataInputStream

B BufferedInputStream

C FileInputStream

D ObjectInputStream

Correct Answer: A. DataInputStream

EXPLANATION

DataInputStream is specifically designed to read primitive data types (int, float, double, etc.) from a binary stream using methods like readInt(), readFloat(), etc.

Test

Q.13 Easy I/O Streams

What happens when you attempt to read from a closed InputStream?

A Returns -1

B Throws IOException

C Returns empty byte array

D Silently ignores the read request

Correct Answer: B. Throws IOException

EXPLANATION

Attempting to read from a closed stream throws an IOException with message 'Stream closed', preventing accidental data processing from invalid sources.

Test

Q.14 Easy I/O Streams

Which class would you use to read and write at arbitrary positions in a file?

A BufferedReader

B FileInputStream

C RandomAccessFile

D PushbackInputStream

Correct Answer: C. RandomAccessFile

EXPLANATION

RandomAccessFile allows reading and writing at arbitrary positions using seek() method, useful for direct access to file contents.

Test

Q.15 Easy I/O Streams

Which of the following is a character-based stream in Java?

A InputStream

B FileInputStream

C FileReader

D DataInputStream

Correct Answer: C. FileReader

EXPLANATION

FileReader is a character-based stream that reads characters from a file. InputStream and its subclasses are byte-based streams.

Test

Q.16 Easy I/O Streams

What is the purpose of the flush() method in PrintWriter?

A Close the stream permanently

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

C Reset the file pointer to the beginning

D Skip unwanted characters from input

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

EXPLANATION

The flush() method clears the internal buffer and forces any buffered output to be written to the underlying stream without closing it.

Test

Q.17 Easy I/O Streams

Which class in Java I/O streams is used to read primitive data types from a binary file?

A DataInputStream

B FileReader

C BufferedInputStream

D InputStreamReader

Correct Answer: A. DataInputStream

EXPLANATION

DataInputStream provides methods like readInt(), readDouble(), readBoolean() to read primitive data types from a binary file.

Test

Q.18 Easy I/O Streams

When using ObjectInputStream, what exception is thrown if the serialVersionUID doesn't match?

A SerializationException

B InvalidClassException

C ClassNotFoundException

D IOException

Correct Answer: B. InvalidClassException

EXPLANATION

InvalidClassException is thrown when deserialized class's serialVersionUID doesn't match the serialized object.

Test

Q.19 Easy I/O Streams

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

A Reading bytes from the file

B Seeking to a specific position

C Writing bytes to the file

D Closing the file

Correct Answer: C. Writing bytes to the file

EXPLANATION

Mode 'r' allows read-only access. Write operations will throw IOException.

Test

Q.20 Easy I/O Streams

What will be the output of reading from a ByteArrayInputStream initialized with bytes [65, 66, 67] after calling read() three times?

A 65, 66, 67

B ABC

C A, B, C

D -1

Correct Answer: A. 65, 66, 67

EXPLANATION

read() returns integer values of bytes. [65, 66, 67] are ASCII values for 'A', 'B', 'C'. Multiple read() calls return these values sequentially.

Test

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