question: public UndoableEdit insertString ( int where , String str ) throws BadLocationException { if ( where >= count || where < 0 ) { throw new BadLocationException ( "Invalid location" , count ) ; } char [ ] chars = str . toCharArray ( ) ; replace ( where , 0 , chars , 0 , chars . length ) ; if ( marks != null ) { updateMarksForInsert ( where , str . length ( ) ) ; } return new InsertUndo ( where , str . length ( ) ) ; }
target:  Inserts a string into the content.