Class FilterReader
java.lang.Object
java.io.Reader
java.io.FilterReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Readable
- Direct Known Subclasses:
PushbackReader
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
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Field Summary
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes the stream and releases any system resources associated with it.void
mark
(int readAheadLimit) Marks the present position in the stream.boolean
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
nullReader, read, read, transferTo
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Field Details
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in
The underlying character-input stream.
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Constructor Details
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FilterReader
Creates a new filtered reader.- Parameters:
in
- a Reader object providing the underlying stream.- Throws:
NullPointerException
- ifin
isnull
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Method Details
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read
Reads a single character.- Overrides:
read
in classReader
- 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
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read
Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.If
len
is zero, then no characters are read and0
is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value-1
is returned; otherwise, at least one character is read and stored intocbuf
.- Specified by:
read
in classReader
- Parameters:
cbuf
- Destination bufferoff
- Offset at which to start storing characterslen
- Maximum number of characters to read- Returns:
- The number of characters read, or -1 if the end of the stream has been reached
- Throws:
IndexOutOfBoundsException
- Ifoff
is negative, orlen
is negative, orlen
is greater thancbuf.length - off
IOException
- If an I/O error occurs
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skip
Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. If the stream is already at its end before this method is invoked, then no characters are skipped and zero is returned.- Overrides:
skip
in classReader
- Parameters:
n
- The number of characters to skip- Returns:
- The number of characters actually skipped
- Throws:
IllegalArgumentException
- Ifn
is negative and the containedReader
'sskip
method throws an IllegalArgumentException for a negative parameterIOException
- If an I/O error occurs
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ready
Tells whether this stream is ready to be read.- Overrides:
ready
in classReader
- 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
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markSupported
public boolean markSupported()Tells whether this stream supports the mark() operation.- Overrides:
markSupported
in classReader
- Returns:
- true if and only if this stream supports the mark operation.
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mark
Marks the present position in the stream.- Overrides:
mark
in classReader
- 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
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reset
Resets the stream.- Overrides:
reset
in classReader
- Throws:
IOException
- If an I/O error occurs
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close
Description copied from class:Reader
Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classReader
- Throws:
IOException
- If an I/O error occurs
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