Writer Classes
Introduction
-
Writeris an abstract class used to write character-oriented data (16-bit Unicode) to output destinations such as files, memory or network connections. -
It is present in the
java.iopackage. -
It provides basic methods like
write()to write single characters, arrays of characters, or strings to output sources. -
Unlike
OutputStreamwhich deals with bytes,Writeris specifically designed to handle characters, making it suitable for text data.
-
Below is the diagram for Writer class hierarchy:
- Each of these subclasses are designed for specific purposes, which are explained below one by one.
1. BufferedWriter
- Description: Writes text to a character output stream efficiently by buffering characters, reducing the number of I/O operations.
- Use in Projects: Commonly used for writing large amounts of text data to files.
-
Example Syntax:
BufferedWriter bw = new BufferedWriter(new FileWriter("file.txt")); bw.write("Hello Java"); bw.close();
2. CharArrayWriter
- Description: Writes characters to a character array, which can be converted to a string or retrieved later.
- Use in Projects: Useful when you need to create strings dynamically or when working with in-memory text data.
-
Example Syntax:
CharArrayWriter caw = new CharArrayWriter(); caw.write("Hello Java"); System.out.println(caw.toString()); caw.close();
3. FilterWriter
- Description: An abstract class for writing filtered character streams. It acts as a base class for subclasses that modify output data.
- Use in Projects: Rarely used directly; extended to implement custom filters.
-
Example Syntax:
// FilterWriter is abstract and cannot be used directly // Example subclass: can be extended for custom filtering
4. OutputStreamWriter
- Description: A bridge between byte streams and character streams. Converts characters into bytes using a specified charset.
- Use in Projects: Commonly used to write characters to byte-oriented destinations (like network sockets).
-
Example Syntax:
OutputStreamWriter osw = new OutputStreamWriter(System.out); osw.write("Hello Java"); osw.close();
5. FileWriter
-
Description: A convenient subclass of
OutputStreamWriterthat is used for writing characters to files. - Use in Projects: Simplifies writing text files without explicitly specifying character encoding (uses platform default).
-
Example Syntax:
FileWriter fw = new FileWriter("file.txt"); fw.write("Hello Java"); fw.close();
6. PipedWriter
-
Description: Writes characters to a connected
PipedReader, enabling communication between threads. - Use in Projects: Useful in multithreaded applications for inter-thread data transfer.
-
Example Syntax:
PipedWriter pw = new PipedWriter(); PipedReader pr = new PipedReader(pw); pw.write("Hello from thread"); pw.close(); pr.close();
7. PrintWriter
-
Description: Writes formatted text to a character output stream and provides convenient methods like
print()andprintln(). - Use in Projects: Commonly used for writing text-based logs or console-like output to files.
-
Example Syntax:
PrintWriter pw = new PrintWriter("file.txt"); pw.println("Hello Java"); pw.close();
8. StringWriter
- Description: Writes characters to a string buffer, which can be converted to a string later.
- Use in Projects: Useful for creating text dynamically in memory before saving or processing.
-
Example Syntax:
StringWriter sw = new StringWriter(); sw.write("Hello Java"); System.out.println(sw.toString()); sw.close();
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