Question

java写代码的时候报这样的错误，是什么问题？

org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.lang.Long]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Long.<init>()
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:107)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveModelAttribute(HandlerMethodInvoker.java:761)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:355)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:170)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:421)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:409)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:774)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at comp.filter.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:141)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NoSuchMethodException: java.lang.Long.<init>()
at java.lang.Class.getConstructor0(Class.java:2706)
at java.lang.Class.getDeclaredConstructor(Class.java:1985)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:104)
... 27 more
@RequestMapping(value = "/announceBody")
public String announcementResisterById(@ModelAttribute("annance")Long id,BindingResult result, HttpSession session, Model model) {
Announcement annc = announcementSer.getAnnouncementById(id);
model.addAttribute("anLists", annc);
return "AnnouncementBodyList";
}
不好意思 刚才没帖代码。。现在帖上来了。我就是要通过ID去获去这一列数据。

Answer 1

哥们,你的代码呢?
java.lang.Long 这个类实例化时必须带一个参数,一个long或String类型的参数,如果不带参数就会报错,因为Long没有Long()这样不带参数的构造函数

Answer 2

没有实例化，是不是没有添加注入或者没写set,get方法

Answer 3

不能实例化，有包没导入

Answer 4

类型错误，你看下hibernate 那部分