IDEA报错 Failed to instantiate [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.()解决办法
今天写Spring的一个案例,使用JdbcTemplate进行数据库查询,报了这个错.如下
![Failed to instantiate [java.lang.Long]: No default constructor found；nested exception is java.lang()](https://ctyun-collect-0531.gdoss.xstore.ctyun.cn/files/2023/06/04/6832613dc9434da08714943205bc7d85.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0xYWURTRg==,size_16,color_FFFFFF,t_70 "Failed to instantiate [java.lang.Long]: No default constructor found；nested exception is java.lang()")
当然错误解决后发现也很简单,我们使用Spring中的那些方法时,只能使用人家提供好的,否则就会出现类似的该方法异常.![Failed to instantiate [java.lang.Long]: No default constructor found；nested exception is java.lang()](https://ctyun-collect-0531.gdoss.xstore.ctyun.cn/files/2023/06/04/00b1d4542068492caa88a2f95ea19e09.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0xYWURTRg==,size_16,color_FFFFFF,t_70 "Failed to instantiate [java.lang.Long]: No default constructor found；nested exception is java.lang()")
这里进行查询返回值是个Long类型,而这个类型是JDK已经定义好的,应该用类型.class,对于自定义类型才使用BeanPropertyRowMapper<>()来搞.
所以以后有空一定要去看看JDK,框架等的源码,帮我们更好的理解.更重要的是理解了我们才可以学习,创新.
