java - 如何从 Observable 中提取最后一个值并返回它？

Question

我正在做一些更多的 RxJava 实验，主要是试图找出适合我的业务的设计模式。我创建了一个简单的航类跟踪应用程序，可以跟踪多个航类，并在航类移动时做出相应 react 。

假设我有一个Collection<Flight>与 Flight对象。每个航类都有一个Observable<Point>指定接收到的最新位置坐标。如何提取最新的Flight对象本身来自可观察的对象，而不必将其保存到整个单独的变量中？有没有get()方法或Observable上类似的东西？还是我想得太势利了？

public final class Flight {

    private final int flightNumber;
    private final String startLocation;
    private final String finishLocation;
    private final Observable<Point> observableLocation;
    private volatile Point currentLocation = new Point(0,0); //prefer not to have this

    public Flight(int flightNumber, String startLocation, String finishLocation) {

        this.flightNumber = flightNumber;
        this.startLocation = startLocation;
        this.finishLocation = finishLocation;
        this.observableLocation = FlightLocationManager.get().flightLocationFeed()
                .filter(f -> f.getFlightNumber() == this.flightNumber)
                .sample(1, TimeUnit.SECONDS)
                .map(f -> f.getPoint());

        this.observableLocation.subscribe(l -> currentLocation = l);
    }
    public int getFlightNumber() { 
        return flightNumber;
    }
    public String getStartLocation() { 
        return startLocation;
    }
    public String getFinishLocation() { 
        return finishLocation;
    }
    public Observable<Point> getObservableLocation() { 
        return observableLocation.last();
    }
    public Point getCurrentLocation() { 
        return currentLocation; //returns the latest observable location
        //would like to operate directly on observable instead of a cached value
    }
}

Answer 1

这是实现此目的的一种方法，主要是创建 BlockingObservable 。但这是不稳定的，因为如果底层可观察对象未完成，它有可能挂起:

observableLocation.toBlocking().last()