[英]java.lang.NullPointerException in a sample program of Hibernate
i am try to run a sample application of hibernate, it give me a error on run time: 我试图运行一个休眠的示例应用程序,它在运行时给我一个错误:
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment). log4j:WARN找不到记录器(org.hibernate.cfg.Environment)的附加程序。
log4j:WARN Please initialize the log4j system properly. log4j:WARN请正确初始化log4j系统。
Exception in thread "main" java.lang.NullPointerException at transaction.rollback(); transaction.rollback();处的线程“ main”中的异常java.lang.NullPointerException
this is in Main.java: 这在Main.java中:
public class Main {
public static void main(String[] args) {
Session session = HibernateUtil.getSessionFactory().openSession();
Transaction transaction = null;
try {
transaction = session.beginTransaction();
Address address = new Address("ABC", "Delhi", "TN", "110001");
Student student = new Student("kumar", address);
session.save(student);
transaction.commit();
} catch (HibernateException e) {
transaction.rollback();
e.printStackTrace();
} finally {
session.close();
}
Should change 应该改变
transaction.rollback();
to 至
if (transaction != null) {
transaction.rollback();
}
as its possible for the assignment of transaction to throw an exception. 尽可能使事务分配引发异常。
If you want to get rid of the Log4J messages, you can add a call to 如果要摆脱Log4J消息,可以添加一个呼叫到
BasicConfigurator.configure();
to setup basic logging 设置基本日志
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