Java、策略模式、泛型和返回类型

Question

我正在实现策略模式:

public interface Stuff<T> {
  T getStuff();
}

public class IntegerStuff implements Stuff<Integer> {
  public Integer getStuff() { .. }
}

public class StringStuff implements Stuff<String> {
   public String getStuff() { .. }
}

现在，我想使用“上下文”来设置策略并执行策略方法:

public class Context() {
   private Stuff stuff;
   public setStrategy(Stuff stuff) { this.stuff = stuff; }

   public Object doStuff() { // ARGH!
      return stuff.getStuff()
   }
}

如何使用泛型，使 Context 类上的 doStuff() 方法的类型可以与所用策略的类型相同？

Answer 1

您还想参数化 Context:

public class Context<T> {
   private Stuff<T> stuff;
   public setStrategy(Stuff<T> stuff) { this.stuff = stuff; }

   public T doStuff() { // ARGH!
      return stuff.getStuff()
   }
}