Java Programming - MCQ Practice Questions

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

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.

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

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

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

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

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

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.

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

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

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.

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.

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

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

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

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

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

Most streams in Java are idempotent regarding close() - calling it multiple times is safe and subsequent calls typically do nothing.

A class must explicitly implement the Serializable interface to be serialized. Static fields are not serialized, and not all classes are serializable by default.

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