#[J](http://jsoftware.com/), 18 bytes

      '''&()[-.'&([-.-.)

       ''&()[-.           the character set, '' stands for '
                &         is the left operand
                 ([    )  the set> itself, ignore <the input
                 (   -.)  the set> except any characters in <input 
                                          [the wrong ones remain]
                 ( -.  )  the set itself> except <the wrong characters