String Object的有关问题

public class HowMany {    public String cc(){        String str="abc";        str=str+"123";        str=str.substring(2,5);        str=str.toUpperCase();        return str.toString();    }    /**     * @param args     */    public static void main(String[] args) {        // TODO Auto-generated method stub        HowMany hw=new HowMany();        hw.cc();//[color=#FF0000]调用此方法，创建了多少个String Object?[/color]    }}