java - 带有扩展的泛型的正确 java 语法

Question

这是我正在努力解决的一段代码。

public class Channel<T extends Something>{
   public Channel(){}
   public void method(T something){}
}

public class Manager{
   private static ArrayList<Channel<? extends Something>> channels
         = new ArrayList<Channel<? extends Something>>();
   public static <T extends Something> void OtherMethod(T foo){
      for(Channel<? extends Something> c : channels)
        c.method(foo);  // this does not work
   }
}

不起作用的行给我编译器错误:

The method method(capture#1-of ? extends Something) in the type Channel<capture#1-of ? extends Something> is not applicable for the arguments (T)

我不明白这个错误。如果我删除 Manager 类中的所有泛型，它可以工作，但类型不安全。我应该如何在正确的 Java 中执行此操作？

Answer 1

您的方法需要一个类型参数 public <T extends Something> void method(T foo)

public class Channel<T extends Something> {
  public Channel() {
  }

  public <T extends Something> void method(T foo) {
  }
}

public class Manager {
   private static ArrayList<Channel<? extends Something>> channels = new ArrayList<Channel<? extends Something>>();

   public static <T extends Something> void OtherMethod(T foo) {
     for (Channel<? extends Something> c : channels)
        c.method(foo); // this does not work
   }
}