Class 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

Fields

Modifier and Type Field Description
protected Reader in

The underlying character-input stream.

Fields declared in class java.io.Reader

lock

Constructors

Modifier Constructor Description
protected FilterReader​(Reader in)

Creates a new filtered reader.

Methods

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

Fields

in

protected Reader in

The underlying character-input stream.

Constructors

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

Methods

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 an I/O error occurs

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

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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/io/FilterReader.html