question: public static String stripCharsInBag ( String s , String bag ) { int i ; StringBuilder stringBuilder = new StringBuilder ( "" ) ; for ( i = 0 ; i < s . length ( ) ; i ++ ) { char c = s . charAt ( i ) ; if ( bag . indexOf ( c ) == - 1 ) stringBuilder . append ( c ) ; } return stringBuilder . toString ( ) ; }
target:  Removes all characters which appear in string bag from string s. 