How would you implement batch processing in JDBC for multiple INSERT operations?

The correct answer is A: Use addBatch() and executeBatch() methods. addBatch() adds SQL command to batch, executeBatch() executes all batched commands at once, improving performance significantly for multiple operations.

What is the output of the following code? interface I1 { default void show() { System.out.println("I1"); } } interface I2 { default void show() { System.out.println("I2"); } } class C implements I1, I2 { public void show() { I1.super.show(); } public

The correct answer is A: I1. When a class implements multiple interfaces with the same default method, it must explicitly override the method. Using I1.super.show() calls I1's default implementation.

Consider: Function f = x -> x * x; What will f.apply(5) return?

The correct answer is A: 25. Function takes an Integer and returns an Integer. f.apply(5) computes 5 * 5 = 25.

Which interface in Java Collections Framework does not allow duplicate elements?

The correct answer is B: Set. Set interface explicitly does not allow duplicate elements. List allows duplicates, Queue is for ordered collections, and Map stores key-value pairs.

Consider this generic interface: interface Comparable { int compareTo(T o); } Which class definition correctly implements this?

The correct answer is A: class MyClass implements Comparable { public int compareTo(MyClass o) { return 0; } }. Option A correctly implements the generic interface by specifying the concrete type parameter as MyClass in the implements clause.

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Java Programming
I/O Streams

Java OOP, collections, multithreading

53 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 41–50 of 53

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.41 Medium I/O Streams

Which statement about ObjectOutputStream.reset() is correct?

A It resets the file pointer to the beginning

B It clears the internal object graph cache to enable re-serialization of identical objects

C It closes the stream and reopens it

D It deletes the serialized file

Correct Answer: B. It clears the internal object graph cache to enable re-serialization of identical objects

EXPLANATION

reset() clears ObjectOutputStream's internal cache of serialized objects, allowing duplicate objects to be serialized again.

Test

Q.42 Medium I/O Streams

A serialized object contains a field marked as 'transient'. What happens to this field when the object is deserialized?

A It retains its original value from before serialization

B It is set to its default value (null for objects, 0 for primitives)

C An exception is thrown during deserialization

D It becomes immutable

Correct Answer: B. It is set to its default value (null for objects, 0 for primitives)

EXPLANATION

Transient fields are excluded from serialization and are initialized to default values upon deserialization.

Test

Q.43 Medium I/O Streams

A Java program needs to read a file containing 10 million integers. Which approach would be most memory-efficient?

A Use FileInputStream with a byte array buffer

B Load entire file into memory using Scanner

C Use DataInputStream with buffering for sequential reading

D Read all bytes at once using Files.readAllBytes()

Correct Answer: C. Use DataInputStream with buffering for sequential reading

EXPLANATION

DataInputStream with buffering allows sequential reading without loading the entire file into memory, making it ideal for large files.

Test

Q.44 Medium I/O Streams

What is the purpose of the skip() method in InputStream?

A Skip the entire stream

B Skip a specified number of bytes in the stream

C Skip to the end of the stream

D Skip error handling

Correct Answer: B. Skip a specified number of bytes in the stream

EXPLANATION

The skip(long n) method skips n bytes in the input stream and returns the number of bytes actually skipped.

Test

Q.45 Medium I/O Streams

Which of the following statements will correctly read a file line by line?

A FileInputStream fis = new FileInputStream("file.txt"); String line = fis.readLine();

B BufferedReader br = new BufferedReader(new FileReader("file.txt")); String line = br.readLine();

C FileReader fr = new FileReader("file.txt"); String line = fr.readLine();

D DataInputStream dis = new DataInputStream(new FileInputStream("file.txt")); String line = dis.readLine();

Correct Answer: B. BufferedReader br = new BufferedReader(new FileReader("file.txt")); String line = br.readLine();

EXPLANATION

BufferedReader's readLine() method is the standard way to read lines. FileInputStream doesn't have readLine(), FileReader doesn't have readLine() either.

Test

Q.46 Medium I/O Streams

What is the mark() method used for in BufferedReader?

A Mark end of stream

B Mark current position in stream for later reset

C Mark data as corrupted

D Mark stream as closed

Correct Answer: B. Mark current position in stream for later reset

EXPLANATION

The mark() method marks the current position in the stream so it can be returned to later using reset(). Requires markSupported() to return true.

Test

Q.47 Medium I/O Streams

Which class allows reading and writing objects to a stream?

A DataInputStream and DataOutputStream

B ObjectInputStream and ObjectOutputStream

C SerializableInputStream

D ByteArrayStream

Correct Answer: B. ObjectInputStream and ObjectOutputStream

EXPLANATION

ObjectInputStream and ObjectOutputStream are used for serialization and deserialization of Java objects. Objects must implement Serializable interface.

Test

Q.48 Medium I/O Streams

What is the difference between FileInputStream and BufferedInputStream?

A No difference; they are aliases

B FileInputStream reads directly from file; BufferedInputStream adds buffering for efficiency

C BufferedInputStream reads characters; FileInputStream reads bytes

D FileInputStream is deprecated in Java 11+

Correct Answer: B. FileInputStream reads directly from file; BufferedInputStream adds buffering for efficiency

EXPLANATION

FileInputStream reads directly from a file byte by byte, while BufferedInputStream wraps another stream and adds buffering to improve performance by reducing I/O operations.

Test

Q.49 Medium I/O Streams

Which of the following creates a bridge between character and byte streams?

A BufferedReader

B InputStreamReader

C DataInputStream

D ObjectInputStream

Correct Answer: B. InputStreamReader

EXPLANATION

InputStreamReader converts a byte stream (InputStream) into a character stream (Reader), acting as a bridge between the two.

Test

Q.50 Medium I/O Streams

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

A ObjectInputStream

B DataInputStream

C BufferedInputStream

D InputStreamReader

Correct Answer: B. DataInputStream

EXPLANATION

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

Test

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