在java中将对象序列化为XML会忽略对象的某些变量字段

I am trying to serialize my object to an xml file, the problem is that some of the instance variables of this object are not written in the xml file. I don't know why are they ignored and how to get the serialize method to write every variable in the xml file. I have noticed that when I set (using the setter) some of these variables are more likely to be written in xml file.I am trying to serialize my object to an xml fi