FileFilter?java.io.boolean accept(File pathname);
Used to filter files or directories based on your logic (e.g., extension, size, name pattern).
Continue readingHere’s a categorized list of the most commonly used methods of the File class:
| Method | Description |
|---|---|
createNewFile() | Creates a new empty file if it doesn’t exist |
delete() | Deletes the file or directory |
deleteOnExit() | Deletes file when JVM exits |
java.io.FileFile?java.io package.in most real-world scenarios, buffering improves performance and is recommended:
readLine(), newLine()That’s why BufferedReader and BufferedWriter are used in 90%+ of text-processing code.
BufferedInputStreamFilterInputStreamInputStreamInputStream in = new BufferedInputStream(new FileInputStream("file.bin"));
InputStreamReaderInputStream → ReaderInputStream is = new FileInputStream("input.txt");
Reader reader = new InputStreamReader(is, "UTF-8");
InputStream| Feature | InputStream / OutputStream | Reader / Writer |
|---|---|---|
| Belong to | java.io package | java.io package |
| Abstract classes | Yes ✅ | Yes ✅ |
| Base for stream hierarchy | Yes ✅ | Yes ✅ |
| Support chaining/wrapping | Yes ✅ | Yes ✅ (e.g., with buffering) |
| Need to be closed | Yes ✅ (implements Closeable) | Yes ✅ (implements Closeable) |
| Support try-with-resources | Yes ✅ | Yes ✅ |
So all four are abstract base classes that handle I/O streams, support stream composition (via decorators like Buffered*), and must be explicitly closed (or auto-closed with try-with-resources).
PrintWriter vs PrintStream| Feature | PrintWriter | PrintStream |
|---|---|---|
| Package | java.io | java.io |
| Extends | Writer (character-based) | OutputStream (byte-based) |
| Works with | Character streams | Byte streams |
| Encoding-aware | ✅ Yes (especially with OutputStreamWriter) | ❌ No — uses platform default charset |
| Methods | print(), println(), printf(), write() | print(), println(), printf(), write() |
| Autoflush | ✅ Optional (with constructor flag) | ✅ Optional (with constructor flag) |
| Can suppress IOExceptions? | ✅ Yes (can check checkError()) | ✅ Yes (can check checkError()) |
| Better for | Text-based files, writers, Unicode | Console output, logging, binary files |
| Example output | Encoded characters (using specified charset) | Raw bytes with system encoding |
Writer OverviewWriter is an abstract class in java.io for writing character data.OutputStream, but designed for writing text (characters and strings) rather than raw bytes.The Reader class is part of Java’s character-based I/O system, introduced to handle text data (as opposed to InputStream which handles raw bytes). Let’s go over the key subclasses and their purposes.