将实现Callable <T>子接口的任务提交到ExecutorService

Question

如何提交任务,它实现的子接口Callable<T>到ExecutorService？

我有一个Callable<T>定义为的子接口:

public interface CtiGwTask<T>
    extends Callable {

    ...
}

它只是定义了一些静态常量,但没有添加任何方法.

然后我有以下方法,其中execService是一个FixedThreadPool实例.

@Override
public CtiGwTaskResult<Integer> postCtiTask(CtiGwTask<CtiGwTaskResult<Integer>> task) {

    Future<CtiGwTaskResult<Integer>> result =
            execService.submit(task);

    try {
        return result.get();

    } catch (InterruptedException | ExecutionException ex) {
        LOGGER.log(Level.FINEST,
                "Could not complete CTIGwTask", ex);
        return new CtiGwTaskResult<>(
                CtiGwResultConstants.CTIGW_SERVER_SHUTTINGDOWN_ERROR,
                Boolean.FALSE,
                "Cannot complete task: CTIGateway server is shutting down.",
                ex);
    }
}

不幸的是,这提供了2个未经检查的转换和1个未经检查的方法调用警告.

...\CtiGwWorkerImpl.java:151: warning: [unchecked] unchecked conversion
            execService.submit(task);
required: Callable<T>
found:    CtiGwTask<CtiGwTaskResult<Integer>>
where T is a type-variable:
  T extends Object declared in method <T>submit(Callable<T>)

...\CtiGwWorkerImpl.java:151: warning: [unchecked] unchecked method invocation: method submit in interface ExecutorService is applied to given types
            execService.submit(task);
required: Callable<T>
found: CtiGwTask<CtiGwTaskResult<Integer>>
where T is a type-variable:
  T extends Object declared in method <T>submit(Callable<T>)

...\CtiGwWorkerImpl.java:151: warning: [unchecked] unchecked conversion
            execService.submit(task);
required: Future<CtiGwTaskResult<Integer>>
found:    Future

如果我将submit呼叫更改为

Future<CtiGwTaskResult<Integer>> result =
    execService.submit( (Callable<CtiGwTaskResult<Integer>>) task);

然后一切似乎都有效但现在我得到一个未经检查的投射警告.

...\src\com\dafquest\ctigw\cucm\CtiGwWorkerImpl.java:151: warning: [unchecked] unchecked cast
            execService.submit((Callable<CtiGwTaskResult<Integer>>) task);
required: Callable<CtiGwTaskResult<Integer>>
found:    CtiGwTask<CtiGwTaskResult<Integer>>

那么我错过了什么？不应该submit()适用于Callable的子类的实例？

Answer 1

您正在使用原始 Callable类型.

更改:

public interface CtiGwTask<T> extends Callable

对此:

public interface CtiGwTask<T> extends Callable<T>