When a static method is called on an instance of a class, what happens?

The correct answer is B: The method is called on the class, not the instance (though syntactically allowed). Static methods belong to the class, not instances. When called on an instance, Java internally calls the method on the class. Static methods cannot access instance variables or use 'this' keyword.

Given the declaration: List listOfLists; Which assignment is valid?

The correct answer is D: listOfLists = new ArrayList();. Nested generics must match exactly or use appropriate wildcards. Only option D provides exact type match. Option B would work with wildcards, but that's not listed correctly here.

Which generic wildcard usage is INCORRECT?

The correct answer is D: List. Nested wildcards like '? extends ? super T' are not allowed. Wildcards cannot be combined or nested.

Which interface does HashMap implement in Java Collections Framework?

The correct answer is A: Map interface. HashMap implements the Map interface which stores key-value pairs. It does not implement Collection, List, or Set interfaces directly.

In JDBC metadata operations, which method is used to retrieve information about table structure, column names, and their data types?

The correct answer is D: Both B and C together. getMetaData() on ResultSet returns ResultSetMetaData which provides column information. getColumnCount() and getColumnName() are methods of ResultSetMetaData used to retrieve structure details.

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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 51–53 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.51 Medium I/O Streams

Which of the following is a filtered stream?

A FileOutputStream

B BufferedOutputStream

C ByteArrayOutputStream

D PipedOutputStream

Correct Answer: B. BufferedOutputStream

EXPLANATION

BufferedOutputStream is a filtered stream that adds buffering capability to an underlying output stream. Filtered streams wrap other streams to add functionality.

Test

Q.52 Medium I/O Streams

What happens when you try to read from a closed stream in Java?

A Returns -1

B Throws IOException

C Returns null

D Blocks indefinitely

Correct Answer: B. Throws IOException

EXPLANATION

Attempting to read from a closed stream throws an IOException. The stream must be open for read operations.

Test

Q.53 Medium I/O Streams

What is the default buffer size of BufferedReader in Java?

A 512 bytes

B 1024 bytes

C 2048 bytes

D 4096 bytes

Correct Answer: C. 2048 bytes

EXPLANATION

BufferedReader has a default buffer size of 8192 characters, but commonly 2048 bytes is used. The exact implementation may vary, but 8192 is the default character buffer.

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Java Programming I/O Streams

Java Programming
I/O Streams