类型安全:来自 Object 的未经检查的强制转换 [英] Type safety: Unchecked cast from Object

问题描述

我尝试将对象强制转换为我的 Action 类，但结果是警告:

I try to cast an object to my Action class, but it results in a warning:

Type safety: Unchecked cast from Object to Action<ClientInterface>

Action<ClientInterface> action = null;
try {
 Object o = c.newInstance();
 if (o instanceof Action<?>) {
  action = (Action<ClientInterface>) o;
 } else {
  // TODO 2 Auto-generated catch block
  throw new InstantiationException();
 }
 [...]

感谢您的帮助

推荐答案

是的 - 这是 键入擦除.如果 o 实际上是 Action 的一个实例，它不会被演员表捕获 - 您只会在尝试使用它时看到问题，传递在 ClientInterface 而不是字符串中.

Yes - this is a natural consequence of type erasure. If o is actually an instance of Action<String> that won't be caught by the cast - you'll only see the problem when you try to use it, passing in a ClientInterface instead of a string.

您可以使用以下方法消除警告:

You can get rid of the warning using:

@SuppressWarnings("unchecked")

作为一个函数注解，但你不能轻易理清根本问题:(

as a function annotation, but you can't easily sort out the underlying problem :(

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