java - 在 DAO 模式中使用泛型

Question

// Domain Class
public class Actor {

    private int id;
    private String firstName;
    private String lastName;
    private Date lastUpdate;

    // getters and setters
}



// DAO Interface
public interface IDao<T> {

    void save(T t);

}



// Concrete Class
public class ActorDao implements IDao {

    @Override
    public void save(Actor actor) {
        // Error: The method save(Actor) of type ActorDao must override or implement a supertype method

    }

}

当IDao的参数为T时，为什么重写的save()不接受Actor？

Answer 1

您需要指定 T 是什么类，如下所示:

public class ActorDao implements IDao<Actor> {