使用通用DAO时出现NoSuchMethodError

Question

I'm trying to use GenericDAO in a project :

public class GenericDao<T> {
    ApplicationContext ctx =
            new AnnotationConfigApplicationContext(SpringMongoConfig.class);
    MongoOperations mongoOperation = (MongoOperations) ctx.getBean("mongoTemplate");

    public void save(T t) {
        mongoOperation.save(t);
    }

    public void delete(final T t) {
        mongoOperation.remove(t);
    }
}

The child class NoteDAO extends GenericDao and there's no need to override save/delete methods. But when I'm trying to use them I get: java.lang.NoSuchMethodError: com.example.dao.NoteDAO.save(Lcom/example/model/Note;)V

Here is my NoteDAO, it's empty:

public class NoteDAO extends GenericDao<Note> {
    public static Logger LOG = Logger.getLogger(NoteDAO.class);
    public static int counter = 0;
}

Why doesn't it work?

Answer 1

解决该问题的一种可能的方法是在NoteDAO中添加一个无参数的构造函数。

Answer 2

I tried to replicate your scenario and it worked for me... See if you have some kind of code:

package com.x.y;

public class GenericDAO<T> {

   public void save(T t) {
       System.out.println("Generic Save");
   }

   public void delete(final T t) {
      System.out.println("Generic Delete");
   }
}

---

package com.x.y;

public class NoteDAO extends GenericDAO<Note> {

   public void persist(){
      save(new Note());
   }

}

---

package com.x.y;

public class Client {
   public static void main(String[] args) {
    NoteDAO nDao = new NoteDAO();
    nDao.save(new Note());   
   }
}

So, when I run Client it prints: "Generic Save".

Just trying to help you.