question: public static String hexStringToAsciiString ( final String hexString ) { final String realText = ( hexString . length ( ) % 2 ) == 0 ? hexString : "0" + hexString ; final StringBuilder stringBuilder = new StringBuilder ( ) ; for ( int i = 0 ; i < realText . length ( ) ; i += 2 ) { final char c1 = realText . charAt ( i ) ; final char c2 = realText . charAt ( i + 1 ) ; if ( ! isHexCharacter ( c1 ) || ! isHexCharacter ( c2 ) ) { throw new IllegalArgumentException ( "Error: Invalid hex string" ) ; } final char code = ( char ) ( ( Character . digit ( c1 , 16 ) << 4 ) + Character . digit ( c2 , 16 ) ) ; stringBuilder . append ( isPrintableCharacter ( code ) ? code : "." ) ; } return stringBuilder . toString ( ) ; }
target:  Converts a hex to ASCII. If the hex string has an odd number of characters, a 0 is added at the end of the string. Example: 414141 is converted to AAA