a_9_5_2_7的专栏

前几天做一个学生选课系统时遇到一个空指针异常具体异常信息如下: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at org.yfl.service.LoginService.loginValidate(LoginService.java:17) at org.yfl.view.Login.act

下面是报错信息: C:\Users\admin\Desktop\src>mvn compiler [INFO] Scanning for projects... [WARNING] [WARNING] Some problems were encountered while building the effective model for com.yfl.maven:HelloMaven:

早上用android studio 运行APP时报如下错误: Error running app:instant Run requires "Tools | Android | Enable ADB integration to be enable