Java compact1, compact2, compact3 java.io Class PushbackReader（JDK8）

Constructor Detail

• PushbackReader

  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

  size - The size of the pushback buffer

  Throws:

  IllegalArgumentException - if size <= 0

• PushbackReader

  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

Method Detail

• read

  public int read()
           throws IOException

  Reads a single character.

  Overrides:

  read in class FilterReader

  Returns:

  The character read, 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.

  Overrides:

  read in class FilterReader

  Parameters:

  cbuf - Destination buffer

  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

• unread

  public void unread(int c)
              throws IOException

  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

  Throws:

  IOException - If the pushback buffer is full, or if some other I/O error occurs

• unread

  public void unread(char[] cbuf,
                     int off,
                     int len)
              throws IOException

  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

  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

• unread

  public void unread(char[] cbuf)
              throws IOException

  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

  Throws:

  IOException - If there is insufficient room in the pushback buffer, or if some other I/O error occurs

• ready

  public boolean ready()
                throws IOException

  Tells whether this stream is ready to be read.

  Overrides:

  ready in class FilterReader

  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

• mark

  public void mark(int readAheadLimit)
            throws IOException

  Marks the present position in the stream. The mark for class PushbackReader always throws an exception.

  Overrides:

  mark in class FilterReader

  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 - Always, since mark is not supported

• reset

  public void reset()
             throws IOException

  Resets the stream. The reset method of PushbackReader always throws an exception.

  Overrides:

  reset in class FilterReader

  Throws:

  IOException - Always, since reset is not supported

• markSupported

  public boolean markSupported()

  Tells whether this stream supports the mark() operation, which it does not.

  Overrides:

  markSupported in class FilterReader

  Returns:

  true if and only if this stream supports the mark operation.

• close

  public void close()
             throws IOException

  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.

  Specified by:

  close in interface Closeable

  Specified by:

  close in interface AutoCloseable

  Overrides:

  close in class FilterReader

  Throws:

  IOException - If an I/O error occurs

• skip

  public long skip(long n)
            throws IOException

  Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached.

  Overrides:

  skip in class FilterReader

  Parameters:

  n - The number of characters to skip

  Returns:

  The number of characters actually skipped

  Throws:

  IllegalArgumentException - If n is negative.

  IOException - If an I/O error occurs