关于StringBuffer和StringBuilder中没有重写方法？

Question

hashCode()和equals()方法均未覆盖StringBuffer和StringBuilder,我是想这幅下面的代码..

    //StringBuffer does not override equals & hashCode
        //StringBuffer s = new StringBuffer("saral");
        //StringBuffer s1 = new StringBuffer("saral");

        StringBuilder s = new StringBuilder("saral");
        StringBuilder s1 = new StringBuilder("saral");          

        //String s = new String("saral");
        //String s1 = new String("saral");

       HashSet set=new HashSet();
        set.add(s);
        set.add(s1);
        set.add(null);
       System.out.println("There are "+set.size()+" elements in the set.");

从而导致在来我是个得到的是3两的情况下,当我使用StringBuffer或StringBuilder字符串的情况下,但2,因为字符串具有覆盖hashCode()和equals()方法,请告知.

Answer 1

StringBuilder/StringBuffer是为更高效的字符串操作而创建的,而不是为商店值创建的.因此,您不应将其用作密钥或实现您的版本.或者只是打电话toString给它.