https://gist.github.com/2414323
有时候,你已经知道计算结果,但是你的接口需要返回一个Future
。与其实现一个长的匿名类,或者扩展AbstractFuture或FutureTask这些本身就很复杂的类,我发现创建一个只实现Future
的小持有者类更简单。我的问题是:类似于我下面写的这个类,在标准库中是否已经存在? 用法:
Future<Boolean> iHaveToReturnAFutureButIAlreadyKnowTheAnswer() {
return new ResolvedFuture(true);
}
代码:
/**
* Used when you need to return a Future, but you already have the answer.
*/
public class ResolvedFuture<T> implements Future<T>{
private final T item;
public ResolvedFuture(T item) {
this.item = item;
}
@Override
public boolean cancel(boolean mayInterruptIfRunning) {
return false;
}
@Override
public boolean isCancelled() {
return false;
}
@Override
public boolean isDone() {
return true;
}
@Override
public T get() throws InterruptedException, ExecutionException {
return item;
}
@Override
public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException {
return item;
}
}