question: public synchronized boolean removeAll ( Collection c ) { Object [ ] elements = getArray ( ) ; int len = elements . length ; if ( len != 0 ) { int newlen = 0 ; Object [ ] temp = new Object [ len ] ; for ( int i = 0 ; i < len ; ++ i ) { Object element = elements [ i ] ; if ( ! c . contains ( element ) ) temp [ newlen ++ ] = element ; } if ( newlen != len ) { setArray ( copyOfRange ( temp , 0 , newlen , Object [ ] . class ) ) ; return true ; } } return false ; }
target:  Removes from this list all of its elements that are contained in the specified collection. This is a particularly expensive operation in this class because of the need for an internal temporary array.