20190506（已解决）Null value was assigned to a property of primitive type setter of xxxxx

Struts Problem Report
Struts has detected an unhandled exception:

Messages:	
Null value was assigned to a property of primitive type setter of com.ninebot.ad.schdBus.busLine.entity.Line.num
File:	org/hibernate/property/BasicPropertyAccessor.java
Line number:	109

Stacktraces
org.hibernate.PropertyAccessException: Null value was assigned to a property of
primitive type setter of com.ninebot.ad.schdBus.busLine.entity.Line.num

通过以上问题反馈，应该是设置了空值
但是将entity中，
private int num；
改成
private Integer num；
报错消失。