调用函数时出现JavaNullPointerException
在java中调用函数时出错。调用函数时出现JavaNullPointerException,java,jakarta-ee,nullpointerexception,Java,Jakarta Ee,Nullpointerexception,在java中调用函数时出错。 返回类型是void,我只是调用它并在其中显示一个字符串 下面是窃听函数的调用: @RequestMapping(method = RequestMethod.POST) public String findDevicesByCriteria(@Valid @ModelAttribute Device device, BindingResult bindingResult, Model uiModel) { if (isCriteriaEmpty(device
返回类型是void,我只是调用它并在其中显示一个字符串 下面是窃听函数的调用:
@RequestMapping(method = RequestMethod.POST)
public String findDevicesByCriteria(@Valid @ModelAttribute Device device, BindingResult bindingResult, Model uiModel) {
if (isCriteriaEmpty(device)) {
uiModel.addAttribute("criteriaEmptyWarning", "error_search_criteria_empty");
return ViewConstants.DEVICE_SEARCH_VIEW;
}
identityService.searchDevices(device.getSerialNumber(), device.getOwner().getSiteName(), device.getIpAdress(), device.getInstallDate(), device.getEndDate()); // the error come from here
return ViewConstants.DEVICE_SEARCH_VIEW;
}
/**
* Search devices.
*
* @param sn the serial number of the device
* @param site the site of it
* @param ipAdress the ip adress of it
* @param installDt the install date of it
* @param endDt the end date of it
* @return the list of device
*/
void searchDevices(String sn, String site, String ipAdress, Date installDt, Date EndDt);
窃听功能界面中的原型:
@RequestMapping(method = RequestMethod.POST)
public String findDevicesByCriteria(@Valid @ModelAttribute Device device, BindingResult bindingResult, Model uiModel) {
if (isCriteriaEmpty(device)) {
uiModel.addAttribute("criteriaEmptyWarning", "error_search_criteria_empty");
return ViewConstants.DEVICE_SEARCH_VIEW;
}
identityService.searchDevices(device.getSerialNumber(), device.getOwner().getSiteName(), device.getIpAdress(), device.getInstallDate(), device.getEndDate()); // the error come from here
return ViewConstants.DEVICE_SEARCH_VIEW;
}
/**
* Search devices.
*
* @param sn the serial number of the device
* @param site the site of it
* @param ipAdress the ip adress of it
* @param installDt the install date of it
* @param endDt the end date of it
* @return the list of device
*/
void searchDevices(String sn, String site, String ipAdress, Date installDt, Date EndDt);
最后是导致问题的函数:
public void searchDevices(String sn, String site, String ipAdress, Date installDt, Date EndDt) {
System.out.println("toto");
}
请指教
在访问值之前,请检查设备是否为空
if(device != null)
{
identityService.searchDevices(device.getSerialNumber(), device.getOwner().getSiteName(), device.getIpAdress(), device.getInstallDate(), device.getEndDate());
}
identityService
或service
中的任何一个尚未初始化,因此为空。然后,当您尝试使用它时,会得到一个NullPointerException
。1.Plz。确认您是否已声明并定义标识服务的bean。(很可能是控制器中的@Autowired,并在SpringBean上下文文件中定义为bean)并纠正发现的差异(如果有)
如果您可以共享整个控制器文件(从调用函数的位置和抛出null指针的行上的调试点),那么确定问题就容易得多。检查以下对象是否为null
identityService
device
device.getOwner()
我做到了,这不是问题,但我忘记了这个有用的验证。谢谢,是的,我的身份服务已声明,@Autowired。bean被声明。