File I/O and NIO

• Bridge classes InputStreamReader / OutputStreamWriter turn a byte stream into a character stream
• Always give the bridge an explicit Charset

• Decorator pattern: each wrapper adds one job around the stream inside it

var br = new BufferedReader(
    new InputStreamReader(
        new FileInputStream(f), UTF_8));

bytes, then decode, then buffer

• try (var r = new BufferedReader(...)) { } closes any AutoCloseable
• Closes even when an exception is thrown
• Closing the outer wrapper closes the inner stream
• Close order is reverse of declaration
• A failing close() is suppressed: read it with getSuppressed()
• The primary exception is not lost

• readLine() returns null at end of file

• Path is an immutable location: Path.of("a","b.txt") or Paths.get(...)
• It may not exist on disk; creating one touches nothing
• Operations are pure string logic, no disk access

• new FileReader(f): platform default before Java 18
• Java 18+ (JEP 400): default is UTF-8
• Still pass StandardCharsets.UTF_8 explicitly

• Always try-with-resources
• Resources close in reverse order of declaration
• close() errors become suppressed: getSuppressed()