PushbackInputStream

• The PushbackInputStream class provides a pushback buffer so a program can "unread" bytes onto the stream.

• The next time data is read from the stream, the "unread" bytes are read.

   public void unread(int b) throws IOException
   public void unread(byte[] data, int offset, int length) throws IOException
   public void unread(byte[] data) throws IOException
  

• By default the buffer is only one byte long, and trying to unread more than that throws an IOException. However you can change the default buffer size with the second constructor:

   public PushbackInputStream(InputStream in)
   public PushbackInputStream(InputStream in, int size)