@SuppressWarnings("rawtypes")
    public boolean retainAll(Collection c) {
        boolean flag = false;
        if (c == null)
            throw new NullPointerException(" null arg! ");
        for ( Iterator it = this.iterator(); it.hasNext();) {
            if ( ! c.contains(it.next())) {
                flag = true;
                it.remove();
            }
            
        }
        return flag;
    }
@SuppressWarnings("rawtypes")
    public boolean retainAll(Collection c) {
        boolean flag = false;
        if (c == null)
            throw new NullPointerException(" null arg! ");
        for ( Iterator it = this.iterator(); it.hasNext();) {
            if ( ! c.contains(it.next())) {
                flag = true;
                it.remove();
            }
            
        }
        return flag;
    }
@ SuppressWarnings ( "rawtypes" ) public boolean retainAll ( Collection c ) { boolean flag = false ; if ( c == null ) throw new NullPointerException ( " null arg! " ) ; for ( Iterator it = this . iterator ( ) ; it . hasNext ( ) ; ) { if ( ! c . contains ( it . next ( ) ) ) { flag = true ; it . remove ( ) ; } } return flag ; }
/*
(non-Javadoc)

@see java.util.Collection#retainAll(java.util.Collection)
/ * ( non - Javadoc )