Module java.base
Package java.io

Class FilterReader

java.lang.Object
java.io.Reader
java.io.FilterReader
All Implemented Interfaces:
Closeable, AutoCloseable, Readable
Direct Known Subclasses:
PushbackReader
public abstract class FilterReader
extends Reader
Abstract class for reading filtered character streams. The abstract class FilterReader itself provides default methods that pass all requests to the contained stream. Subclasses of FilterReader 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 Reader in
    The underlying character-input stream.

    Fields declared in class java.io.Reader

    lock

  • Constructor Summary

    Constructors 
    Modifier Constructor Description
    protected FilterReader​(Reader in)
    Creates a new filtered reader.

  • Method Summary

    Modifier and Type Method Description
    void mark​(int readAheadLimit)
    Marks the present position in the stream.
    boolean markSupported()
    Tells whether this stream supports the mark() operation.
    int read()
    Reads a single character.
    int read​(char[] cbuf, int off, int len)
    Reads characters into a portion of an array.
    boolean ready()
    Tells whether this stream is ready to be read.
    void reset()
    Resets the stream.
    long skip​(long n)
    Skips characters.

    Methods declared in class java.io.Reader

    close, nullReader, read, read, transferTo

    Methods declared in class java.lang.Object

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

  • Field Details

    • in

      protected Reader in
      The underlying character-input stream.

  • Constructor Details

    • FilterReader

      protected FilterReader​(Reader in)
      Creates a new filtered reader.
      Parameters:
      in - a Reader object providing the underlying stream.
      Throws:
      NullPointerException - if in is null

  • Method Details

    • read

      public int read() throws IOException
      Reads a single character.
      Overrides:
      read in class Reader
      Returns:
      The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached
      Throws:
      IOException - If an I/O error occurs

    • read

      public int read​(char[] cbuf, int off, int len) throws IOException
      Reads characters into a portion of an array.
      Specified by:
      read in class Reader
      Parameters:
      cbuf - Destination buffer
      off - Offset at which to start storing characters
      len - Maximum number of characters to read
      Returns:
      The number of characters read, or -1 if the end of the stream has been reached
      Throws:
      IOException - If an I/O error occurs
      IndexOutOfBoundsException - If off is negative, or len is negative, or len is greater than cbuf.length - off

    • skip

      public long skip​(long n) throws IOException
      Skips characters.
      Overrides:
      skip in class Reader
      Parameters:
      n - The number of characters to skip
      Returns:
      The number of characters actually skipped
      Throws:
      IOException - If an I/O error occurs

    • ready

      public boolean ready() throws IOException
      Tells whether this stream is ready to be read.
      Overrides:
      ready in class Reader
      Returns:
      True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.
      Throws:
      IOException - If an I/O error occurs

    • markSupported

      public boolean markSupported()
      Tells whether this stream supports the mark() operation.
      Overrides:
      markSupported in class Reader
      Returns:
      true if and only if this stream supports the mark operation.

    • mark

      public void mark​(int readAheadLimit) throws IOException
      Marks the present position in the stream.
      Overrides:
      mark in class Reader
      Parameters:
      readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail.
      Throws:
      IOException - If an I/O error occurs

    • reset

      public void reset() throws IOException
      Resets the stream.
      Overrides:
      reset in class Reader
      Throws:
      IOException - If an I/O error occurs