Another of those JavaProblems...

If you write byte values to an '''O''''''utputStream''' you pass an int value between -128 and +127.  However, if you read byte values from an '''I''''''nputStream''' you get an int value between 0 and 255.

If you want to perform calculations on the int representation of a byte value read from an '''I''''''nputStream''', cast to a byte and then back to an int to perform sign extension.

E.g:

    int value_read = in.read();
    if( value_read == -1 ) {
        // handle EOF
    }
 
    int byte_value = (int)(byte)value_read;
    // Perform calculations on the value of the byte

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CategoryJavaPlatform