FilterWriter (Java SE 22 & JDK 22)
Description: declaration: module: java.base, package: java.io, class: FilterWriter
Keywords: java.io.FilterWriter class

Module java.base
Package java.io

# Class FilterWriter

java.lang.Object
java.io.Writer
java.io.FilterWriter

All Implemented Interfaces:
  `Closeable`, `Flushable`, `Appendable`, `AutoCloseable`

public abstract class FilterWriter extends Writer
Abstract class for writing filtered character streams. The abstract class `FilterWriter` itself provides default methods that pass all requests to the contained stream. Subclasses of `FilterWriter` should override some of these methods and may also provide additional methods and fields.

Since:
  1.1

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected Writer`
  `out`
  The underlying character-output stream.

  ### Fields declared in class java.io.Writer

  `lock`

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `FilterWriter(Writer out)`
  Create a new filtered writer.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `void`
  `close()`
  Closes the stream, flushing it first.
  `void`
  `flush()`
  Flushes the stream.
  `void`
  `write(char[] cbuf, int off, int len)`
  Writes a portion of an array of characters.
  `void`
  `write(int c)`
  Writes a single character.
  `void`
  `write(String str, int off, int len)`
  Writes a portion of a string.

  ### Methods declared in class java.io.Writer

  `append, append, append, nullWriter, write, write`

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### out

    protected Writer out
    The underlying character-output stream.

- ## Constructor Details

  - ### FilterWriter

    protected FilterWriter(Writer out)
    Create a new filtered writer.
    Parameters:
      `out` - a Writer object to provide the underlying stream.
    Throws:
      `NullPointerException` - if `out` is `null`

- ## Method Details

  - ### write

    public void write(int c) throws IOException
    Writes a single character.
    Overrides:
      `write` in class `Writer`
    Parameters:
      `c` - int specifying a character to be written
    Throws:
      `IOException` - If an I/O error occurs

  - ### write

    public void write(char[] cbuf, int off, int len) throws IOException
    Writes a portion of an array of characters.
    Specified by:
      `write` in class `Writer`
    Parameters:
      `cbuf` - Buffer of characters to be written
      `off` - Offset from which to start reading characters
      `len` - Number of characters to be written
    Throws:
      `IndexOutOfBoundsException` - If the values of the `off` and `len` parameters cause the corresponding method of the underlying `Writer` to throw an `IndexOutOfBoundsException`
      `IOException` - If an I/O error occurs

  - ### write

    public void write(String str, int off, int len) throws IOException
    Writes a portion of a string.
    Overrides:
      `write` in class `Writer`
    Parameters:
      `str` - String to be written
      `off` - Offset from which to start reading characters
      `len` - Number of characters to be written
    Throws:
      `IndexOutOfBoundsException` - If the values of the `off` and `len` parameters cause the corresponding method of the underlying `Writer` to throw an `IndexOutOfBoundsException`
      `IOException` - If an I/O error occurs

  - ### flush

    public void flush() throws IOException
    Flushes the stream.
    Specified by:
      `flush` in interface `Flushable`
    Specified by:
      `flush` in class `Writer`
    Throws:
      `IOException` - If an I/O error occurs

  - ### close

    public void close() throws IOException
    Description copied from class: `Writer`
    Closes the stream, flushing it first. Once the stream has been closed, further write() or flush() invocations will cause an IOException to be thrown. Closing a previously closed stream has no effect.
    Specified by:
      `close` in interface `AutoCloseable`
    Specified by:
      `close` in interface `Closeable`
    Specified by:
      `close` in class `Writer`
    Throws:
      `IOException` - If an I/O error occurs