java.io
public
abstract
class
java.io.FilterReader
FilterReader is a class which takes a Reader and filters the input
in some way. The filtered view may be a buffered view or one which
uncompresses data before returning characters read.
Known Direct Subclasses
PushbackReader |
PushbackReader is a filter class which allows chars read to be pushed back
into the stream so that they can be reread. |
Summary
Fields
protected |
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|
Reader |
in |
The target Reader which is being filtered. |
protected |
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Object |
lock |
The object used to synchronize access to the reader. |
Protected Constructors
Public Methods
Methods inherited
from class
java.io.Reader
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
Details
Fields
protected
Reader
in
The target Reader which is being filtered.
Protected Constructors
protected
FilterReader(Reader in)
Constructs a new FilterReader on the Reader
in
. All reads
are now filtered through this Reader.
Parameters
in
| The non-null Reader to filter reads on.
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Public Methods
public
void
close()
Close this FilterReader. This implementation closes the target Reader.
Throws
IOException
| If an error occurs attempting to close this Reader.
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public
synchronized
void
mark(int readlimit)
Set a Mark position in this FilterReader. The parameter
readLimit
indicates how many characters can be read before
a mark is invalidated. Sending reset() will reposition the Reader back to
the marked position provided
readLimit
has not been
surpassed.
This implementation sets a mark in the target Reader.
Parameters
readlimit
| the number of characters to be able to read before
invalidating the mark. |
Throws
IOException
| If an error occurs attempting mark this Reader.
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public
boolean
markSupported()
Returns a boolean indicating whether or not this FilterReader supports
mark() and reset(). This implementation returns whether or not the target
Reader supports marking.
Returns
- indicates whether or not mark() and reset() are supported.
public
int
read(char[] buffer, int offset, int count)
Reads at most
count
chars from this FilterReader and
stores them in char array
buffer
starting at offset
offset
. Answer the number of chars actually read or -1 if
no chars were read and end of reader was encountered. This implementation
reads chars from the target reader.
Parameters
buffer
| the char array in which to store the read chars. |
offset
| the offset in buffer to store the read chars. |
count
| the maximum number of chars to store in buffer . |
Returns
- the number of chars actually read or -1 if end of reader.
Throws
IOException
| If an error occurs attempting to read from this Reader.
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public
int
read()
Reads a single char from this FilterReader and returns the result as an
int. The 2 lowest order bytes are returned or -1 of the end of reader was
encountered. This implementation returns a char from the target Reader.
Returns
- The byte read or -1 if end of reader.
Throws
IOException
| If an error occurs attempting to read from this Reader.
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public
boolean
ready()
Returns a
boolean
indicating whether or not this Reader is
ready to be read without blocking. If the result is
true
,
the next
read()
will not block. If the result is
false
this Reader may or may not block when
read()
is sent.
Returns
true
if the receiver will not block when
read()
is called, false
if unknown
or blocking will occur.
Throws
IOException
| If the Reader is already closed or some other IO error
occurs.
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public
void
reset()
Reset this Readers position to the last
mark()
location.
Invocations of
read()/skip()
will occur from this new
location. If this Reader was not marked, the implementation of
reset()
is implementation specific. See the comment for
the specific Reader subclass for implementation details. The default
action is to throw
IOException
.
Throws
IOException
| if a problem occurred or the target Reader does not support
mark()/reset() .
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public
long
skip(long count)
Skips
count
number of characters in this Reader.
Subsequent
read()
's will not return these characters
unless
reset()
is used. The default implementation is to
skip chars in the filtered Reader.
Parameters
count
| the maximum number of characters to skip. |
Returns
- the number of characters actually skipped.
Throws
IOException
| If the Reader is already closed or some other IO error
occurs.
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