The abstract InputStream.read() method reads a single byte from an input source and returns its value as an int in the range 0 to 255. It will return -1 only when the end of the input stream has been reached. The similar Similarly, the abstract Reader.read() method reads a single character, and returns its value as an int in the range 0 to 65,535. It also returns -1 only when the end of the stream has been reached. Both methods are meant to be overridden in subclasses.
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