question: public static String urlDecode ( String encoded ) { int length = encoded . length ( ) ; byte [ ] buff = new byte [ length ] ; int j = 0 ; for ( int i = 0 ; i < length ; i ++ ) { char ch = encoded . charAt ( i ) ; if ( ch == '+' ) { buff [ j ++ ] = ' ' ; } else if ( ch == '%' ) { buff [ j ++ ] = ( byte ) Integer . parseInt ( encoded . substring ( i + 1 , i + 3 ) , 16 ) ; i += 2 ; } else { if ( SysProperties . CHECK ) { if ( ch > 127 || ch < ' ' ) { throw new IllegalArgumentException ( "Unexpected char " + ( int ) ch + " decoding " + encoded ) ; } } buff [ j ++ ] = ( byte ) ch ; } } String s = new String ( buff , 0 , j , Constants . UTF8 ) ; return s ; }
target:  Decode the URL to a string.