7

我需要测试一个实例是否完全属于给定类型。但是，如果为超类型测试子类型（案例 3），似乎 instanceof 也会返回 true。我以前从来不知道这一点，我很惊讶。我在这里做错了吗？我如何准确测试给定类型？

//..

class DataSourceEmailAttachment extends EmailAttachment

//...

EmailAttachment emailAttachment = new EmailAttachment();
DataSourceEmailAttachment emailAttachmentDS = new DataSourceEmailAttachment();

    if (emailAttachment instanceof EmailAttachment){
        System.out.println(" 1");
    }
    if (emailAttachment instanceof DataSourceEmailAttachment){
        System.out.println(" 2");
    }

    if (emailAttachmentDS instanceof EmailAttachment){
        System.out.println(" 3 ");
    }
    if (emailAttachmentDS instanceof DataSourceEmailAttachment){
        System.out.println(" 4");
    }

结果：

 1
 3 
 4

我想避免 case 3，我只想要“完全匹配”（案例 1 和 4）我如何测试它们？

4

1 回答 1

19 
if( emailAttachment.getClass().equals(EmailAttachment.class) )
于 2010-03-14T19:03:42.813 回答