Question

I am going through the oracle API for java.io.RandomAccessFile class.

There’s method called read() in the class which reads byte of data from the file passed to the constructor:-

public int read()
throws IOException

Reads a byte of data from this file. The byte is returned as an
integer in the range 0 to 255 (0x00-0x0ff). This method blocks if no
input is yet available.

Although RandomAccessFile is not a subclass of InputStream, this
method behaves in exactly the same way as the InputStream.read()
method of InputStream.

Returns:
the next byte of data, or -1 if the end of the file has been reached. Throws:
IOException – if an I/O error occurs. Not thrown if end-of-file has been reached.

I am confused, does it mean to say that it reads 8 bits of data from the file passed to the constructor and convert the read contents to int.

Any suggestions?

Answer 1

What is confusing you, exactly?

Yes, it reads one byte of data, which is 8 bits, and returns it as an integer value in the inclusive range 0..255. So if the file in question happens to be a text file, and the first character is a capital ‘A’, read() will return 65.

It returns an int instead of a byte so that it can return the full range 0..255 as a positive number, and still have -1 available as a sentinel value for end-of-file (though arguably an exception would have been a better way to do that).