1. Variables Are Not Boxes # Think variables as sticky notes a = [1, 2, 3] b = a a.append(4) print b # [1, 2, 3, 4] # 1. The object is created before the assignment. So variable is # assigned to an object, not the other way around. 2. Identity, Equal…

Object References, Mutability, and Recycling 本章章节: Variables Are Not Boxes identity , Equality ,  Aliases Copies are shallow by default Function Parameters as references del and Garbage Collection Weak References Tricks Python Plays with Immutable Va…

异常1:not-null property references a null or transient value解决方法:将“一对多”关系中的“一”方,not-null设置为false(参考资料:http://www.thearcmind.com/confluence/pages/viewpage.action?pageId=212) 异常2:org.hibernate.TransientObjectException: object references an unsaved transi…

在保存ManyToMany  时出现异常: org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.TransientObjectException: object references an unsaved transient instance 如图: 出现原因:单向ManyToMany保存顺序反了,应当先保存主控端permission对象 错误代码: @Transactional(readOnly=f…

NOTE Nulling out object references should be the exception rather than the norm. Another common source of memory leaks is caches. Once you put an object reference into a cache, it's easy to forget that it's there and leave it in the cache long after…

声明:原创作品,转载时请注明文章来自SAP师太技术博客( 博/客/园www.cnblogs.com):www.cnblogs.com/jiangzhengjun,并以超链接形式标明文章原始出处,否则将追究法律责任!原文链接:http://www.cnblogs.com/jiangzhengjun/p/4263761.html 有点像Java里定义一个对应引用一样,但Java里没有直接对某个基本变量定义一个引用,除非使用基本类型所对应的包装类型,JDK5后好像支持自动装箱与自动拆箱了吧.可以把引用…

hibernate : object references an unsaved transient instance 该错误是操作顺序的问题,比如: save或update顺序问题---比方学生表和班级表..学生表里有班级ID的外键.一对多的关系.你save的时候应该先save班级,再save学生. . 否则学生的外键没有相应的值,引发异常.…

今天在使用一对多,多对一保存数据的时候出现了这个错误 Hibernate错误: Exception in thread "main" org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: zhongfucheng.domain.Employee 为啥出现这个错误呢???在保…

本片博文整理关于Hibernate中级联策略cascade和它导致的异常: Exception in thread "main" org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.mao.Address 关于这个异常应该是Hibernate初学者经常遇到的,导致…

object references an unsaved transient instance save the transient instance before flushing 对象引用未保存的瞬态实例,在刷新前保存瞬态实例 错误实例: mortgageInfoDTO  MortgagePersonDTO两者关系 MortgagePersonDTO中包含mortgageInfoDTO  对象 前提:mortgageInfoDTO  MortgagePersonDTO 已存在数据库中 且新建…