A character-stream reader that allows characters to be pushed back into the stream.
Inherited Field Summary
Public Constructor Summary
PushbackReader(Reader in, int size)
Creates a new pushback reader with a pushback buffer of the given size.
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Public Method Summary
void |
close()
Closes the stream and releases any system resources associated with
it.
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void |
mark(int readAheadLimit)
Marks the present position in the stream.
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boolean |
markSupported()
Tells whether this stream supports the mark() operation, which it does
not.
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int |
read()
Reads a single character.
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int |
read(char[] cbuf, int off, int len)
Reads characters into a portion of an array.
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boolean |
ready()
Tells whether this stream is ready to be read.
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void |
reset()
Resets the stream.
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long |
skip(long n)
Skips characters.
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void |
unread(char[] cbuf, int off, int len)
Pushes back a portion of an array of characters by copying it to the
front of the pushback buffer.
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void |
unread(char[] cbuf)
Pushes back an array of characters by copying it to the front of the
pushback buffer.
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void |
unread(int c)
Pushes back a single character by copying it to the front of the
pushback buffer.
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Inherited Method Summary
Public Constructors
public PushbackReader (Reader in, int size)
Creates a new pushback reader with a pushback buffer of the given size.
Parameters
in | The reader from which characters will be read |
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size | The size of the pushback buffer |
Throws
IllegalArgumentException | if size <= 0
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public PushbackReader (Reader in)
Creates a new pushback reader with a one-character pushback buffer.
Parameters
in | The reader from which characters will be read |
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Public Methods
public void close ()
Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), unread(), ready(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.
Throws
IOException | If an I/O error occurs |
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public void mark (int readAheadLimit)
Marks the present position in the stream. The mark
for class PushbackReader
always throws an exception.
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. |
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Throws
IOException | Always, since mark is not supported |
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public boolean markSupported ()
Tells whether this stream supports the mark() operation, which it does not.
Returns
- true if and only if this stream supports the mark operation.
public int read ()
Reads a single character.
Returns
- The character read, or -1 if the end of the stream has been reached
Throws
IOException | If an I/O error occurs |
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public int read (char[] cbuf, int off, int len)
Reads characters into a portion of an array.
Parameters
cbuf | Destination buffer |
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off | Offset at which to start writing 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 |
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public boolean ready ()
Tells whether this stream is ready to be read.
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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public void reset ()
Resets the stream. The reset
method of
PushbackReader
always throws an exception.
Throws
IOException | Always, since reset is not supported |
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public long skip (long n)
Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.
Parameters
n | The number of characters to skip |
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Returns
- The number of characters actually skipped
Throws
IllegalArgumentException | If n is negative. |
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IOException | If an I/O error occurs |
public void unread (char[] cbuf, int off, int len)
Pushes back a portion of an array of characters by copying it to the
front of the pushback buffer. After this method returns, the next
character to be read will have the value cbuf[off]
, the
character after that will have the value cbuf[off+1]
, and
so forth.
Parameters
cbuf | Character array |
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off | Offset of first character to push back |
len | Number of characters to push back |
Throws
IOException | If there is insufficient room in the pushback buffer, or if some other I/O error occurs |
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public void unread (char[] cbuf)
Pushes back an array of characters by copying it to the front of the
pushback buffer. After this method returns, the next character to be
read will have the value cbuf[0]
, the character after that
will have the value cbuf[1]
, and so forth.
Parameters
cbuf | Character array to push back |
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Throws
IOException | If there is insufficient room in the pushback buffer, or if some other I/O error occurs |
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public void unread (int c)
Pushes back a single character by copying it to the front of the
pushback buffer. After this method returns, the next character to be read
will have the value (char)c
.
Parameters
c | The int value representing a character to be pushed back |
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Throws
IOException | If the pushback buffer is full, or if some other I/O error occurs |
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