No default constructor for entity

Caused by: org.hibernate.InstantiationException: No default constructor for entity: com.vtradex.wms.server.model.bc.WmsBcClassesHead
	at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:84)
	at org.hibernate.tuple.PojoInstantiator.instantiate(PojoInstantiator.java:100)
	at org.hibernate.tuple.entity.AbstractEntityTuplizer.instantiate(AbstractEntityTuplizer.java:351)
	at org.hibernate.persister.entity.AbstractEntityPersister.instantiate(AbstractEntityPersister.java:3539)
	at org.hibernate.impl.SessionImpl.instantiate(SessionImpl.java:1275)
	at org.hibernate.impl.SessionImpl.instantiate(SessionImpl.java:1264)
	at org.hibernate.loader.Loader.instanceNotYetLoaded(Loader.java:1290)
	at org.hibernate.loader.Loader.getRow(Loader.java:1197)
	at org.hibernate.loader.Loader.getRowFromResultSet(Loader.java:568)
	at org.hibernate.loader.Loader.doQuery(Loader.java:689)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:224)
	at org.hibernate.loader.Loader.loadEntity(Loader.java:1784)
	at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:48)
	at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:42)
	at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:2977)
	at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:393)
	at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:374)
	at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:137)
	at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:193)
	at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:101)
	at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:878)
	at org.hibernate.impl.SessionImpl.get(SessionImpl.java:815)
	at org.hibernate.impl.SessionImpl.get(SessionImpl.java:808)
	at org.springframework.orm.hibernate3.HibernateTemplate$1.doInHibernate(HibernateTemplate.java:460)
	at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:362)
	at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:454)
	at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:448)
	at com.vtradex.thorn.server.dao.hibernate.HibernateCommonDao.load(HibernateCommonDao.java:65)
	at com.vtradex.thorn.server.service.pojo.DefaultGridQueryManager.load(DefaultGridQueryManager.java:95)

 如果是modify屏，对象没有增加无参构造方法，会报这个错误。增加无参构造方法即可。

public WmsBcClassesHead(){

super();

// TODO Auto-generated constructor stub

}