如何通过 RxJava 中的动态列表创建观察者? [英] How can I create an Observer over a dynamic list in RxJava?

问题描述

我需要在一个不断变化(添加元素)的数组上创建一个观察者.

I need to create an Observer over an array which is constantly changing (adding elements).

我正在使用 Obserable.from(Iterable) 但它似乎在 ArrayList 上创建了 Observable，就像创建时一样.

I am using Obserable.from(Iterable) but it seems that it creates the Observable over the ArrayList as it is at the moment of the creation.

我需要在每次 ArrayList 添加新元素时通知观察者并执行操作.

I need the Observer to be notified and the Action to be executed everytime the ArrayList gets a new element added.

推荐答案

你去吧.感谢 RxJava Google Group 上的 Dávid Karnok

There you go. Thanks to Dávid Karnok on RxJava Google Group

import java.util.ArrayList;
import java.util.List;

import rx.Observable;
import rx.subjects.PublishSubject;

public class ObservableListExample {

    public static class ObservableList<T> {

        protected final List<T> list;
        protected final PublishSubject<T> onAdd;

        public ObservableList() {
            this.list = new ArrayList<T>();
            this.onAdd = PublishSubject.create();
        }
        public void add(T value) {
            list.add(value);
            onAdd.onNext(value);
        }
        public Observable<T> getObservable() {
            return onAdd;
        }
    }

    public static void main(String[] args) throws Exception {
        ObservableList<Integer> olist = new ObservableList<>();

        olist.getObservable().subscribe(System.out::println);

        olist.add(1);
        Thread.sleep(1000);
        olist.add(2);
        Thread.sleep(1000);
        olist.add(3);
    }
}

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