报错如下：
Exception in thread "main" java.lang.NullPointerException
at dao.impl.UserDaoImpl.checkUser(UserDaoImpl.java:25)
at test.UserTest1.main(UserTest1.java:18)
public class UserDaoImpl implements UserDao{
public boolean checkUser(User user){
DBUtil dbu=new DBUtil();
String sql="select * from user where uid=? and upassword=?";
try{
java.sql.PreparedStatement pstmt=dbu.openConnection().prepareStatement(sql); //这行为报错第25行
pstmt.setString(1,user.getUid());
pstmt.setString(2,user.getUpassword());
java.sql.ResultSet rs = pstmt.executeQuery();
if(rs.next()){
return true;
}
}catch(SQLException ex){
Logger.getLogger(UserDaoImpl.class.getName()).log(Level.SEVERE,null,ex);
return false;
}
return false;
}
另一个报错如下
public class UserTest1 {
public static void main(String[] args) {
UserDaoImpl udi = new UserDaoImpl();
User u=new User("1122900115","931115");
if(udi.checkUser(u)){ //这行为报错第8行
System.out.println("ok");
}
else
System.out.println("false");
}
}