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java.lang.Objectjava.io.Reader
public abstract class Reader
Reader is an Abstract class for reading Character Streams. Subclasses of
Reader must implement the methods read(char[], int, int) and
close().
Writer| Field Summary | |
|---|---|
protected Object |
lock
The object used to synchronize access to the reader. |
| Constructor Summary | |
|---|---|
protected |
Reader()
Constructs a new character stream Reader using this as the
Object to synchronize critical regions around. |
protected |
Reader(Object lock)
Constructs a new character stream Reader using lock as the
Object to synchronize critical regions around. |
| Method Summary | |
|---|---|
abstract void |
close()
Close this Reader. |
void |
mark(int readLimit)
Set a Mark position in this Reader. |
boolean |
markSupported()
Answers a boolean indicating whether or not this Reader supports mark() and reset(). |
int |
read()
Reads a single character from this reader and returns the result as an int. |
int |
read(char[] buf)
Reads characters from this Reader and stores them in the character array buf starting at offset 0. |
abstract int |
read(char[] buf,
int offset,
int count)
Reads at most count characters from this Reader and stores
them at offset in the character array buf. |
boolean |
ready()
Answers a boolean indicating whether or not this Reader is
ready to be read without blocking. |
void |
reset()
Reset this Readers position to the last mark() location. |
long |
skip(long count)
Skips count number of characters in this Reader. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, getClass, hashCode, println, toString |
| Field Detail |
|---|
protected Object lock
| Constructor Detail |
|---|
protected Reader()
this as the
Object to synchronize critical regions around.
protected Reader(Object lock)
lock as the
Object to synchronize critical regions around.
lock - the Object to synchronize critical regions
around.| Method Detail |
|---|
public abstract void close()
throws IOException
IOException - If an error occurs attempting to close this Reader.
public void mark(int readLimit)
throws IOException
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 default implementation simply throws IOException and concrete subclasses must provide their own implementations.
readLimit - an int representing how many characters must be read before
invalidating the mark.
IOException - If an error occurs attempting mark this Reader.public boolean markSupported()
true if mark() and reset() are supported,
false otherwise. This implementation returns
false.
public int read()
throws IOException
IOException - If the Reader is already closed or some other IO error
occurs.
public int read(char[] buf)
throws IOException
buf starting at offset 0. Returns the number of characters
actually read or -1 if the end of reader was encountered.
buf - character array to store the read characters
IOException - If the Reader is already closed or some other IO error
occurs.
public abstract int read(char[] buf,
int offset,
int count)
throws IOException
count characters from this Reader and stores
them at offset in the character array buf.
Returns the number of characters actually read or -1 if the end of reader
was encountered.
buf - character array to store the read charactersoffset - offset in buf to store the read characterscount - how many characters should be read in
IOException - If the Reader is already closed or some other IO error
occurs.
public boolean ready()
throws IOException
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.
true if the receiver will not block when
read() is called, false if unknown
or blocking will occur.
IOException - If the Reader is already closed or some other IO error
occurs.
public void reset()
throws IOException
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.
IOException - If a problem occured or the receiver does not support
mark()/reset().
public long skip(long count)
throws IOException
count number of characters in this Reader.
Subsequent read()'s will not return these characters
unless reset() is used. This method may perform multiple
reads to read count characters.
count - how many characters should be passed over
IOException - If the Reader is closed when the call is made or if an IO
error occurs during the operation.
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