Java 重寫抽象泛型方法

Question

我有以下代碼

public abstract class Event {
    public void fire(Object... args) {
        // tell the event handler that if there are free resources it should call 
        // doEventStuff(args)
    }

    // this is not correct, but I basically want to be able to define a generic 
    // return type and be able to pass generic arguments. (T... args) would also 
    // be ok
    public abstract <T, V> V doEventStuff(T args);
}

public class A extends Event {
   // This is what I want to do
   @Overide
   public String doEventStuff(String str) {
      if(str == "foo") { 
         return "bar";
      } else {
         return "fail";
      }
   }
}

somewhere() {
  EventHandler eh = new EventHandler();
  Event a = new A();
  eh.add(a);
  System.out.println(a.fire("foo")); //output is bar
}

但是我不知道該怎么做，因為我不能用特定的東西覆蓋doEventStuff 。

有誰知道如何做到這一點？

Answer 1

目前還不清楚您要做什么，但也許您只需要使Event本身通用：

public abstract class Event<T, V>
{
    public abstract V doEventStuff(T args);
}

public class A extends Event<String, String>
{
    @Override public String doEventStuff(String str)
    {
        ...
    }
}

Answer 2

您正在使用 generics 但您沒有提供綁定。

public abstract class Event<I, O> { // <-- I is input O is Output
  public abstract O doEventStuff(I args);
}

public class A extends Event<String, String> { // <-- binding in the impl.
  @Override
    public String doEventStuff(String str) {
  }
}

或者更簡單，只有一個通用綁定......

public abstract class Event<T> { // <-- only one provided
  public abstract T doEventStuff(T args);
}

public class A extends Event<String> { // <-- binding the impl.

  @Override
    public String doEventStuff(String str) {
  }
}

Answer 3

這仍然不適合我。 我有以下代碼：

public interface Container<T extends MyEntity> {
...
}


public class MyConcreteContainer implements Container<MyContreteEntity> {
   ...
}

public abstract class MyAbstractClass<T extends MyEntity> {

  public abstract String doStuff(Container<T> container);
}

public class MyConcreteEntity implements MyEntity {
   ...
}

public class MyConcreteImplementedClass extends MyAbstractClass<MyContreteEntity> {
  
  @Override
  public String doStuff(MyConcreteContainer container) {
    ...
  }
}

由於MyConcreteContainer是通用Container的實現，為什么我的編譯器沒有識別出我已經正確地覆蓋了doStuff方法？