RxJava2 过滤器列表<对象> [英] RxJava2 filter List&lt;Object&gt;

问题描述

我正在尝试使用 RxJava2 过滤列表，以便列表中的每个项目(对象)都应该通过验证检查，并且我得到一个结果列表，其中只有通过该测试的项目.例如，如果我的对象具有以下结构，

I'm trying to filter a List with RxJava2 such that each item (object) in the list should pass a validation check and I get a resulting List with only items that pass that test. For instance if my Object had the following structure,

class MyClassA {
    int value1;
    int value2;
}

我只想获取 value2 为 10 的项目列表.

I want to only get the list of items where the value2 is 10.

我有一个 API 调用函数，它返回一个列表的 Observable，即 Observable> 如下，

I have an API call function that returns an Observable of List, i.e. Observable<List<MyClassA>> as follows,

apiService.getListObservable()
    .subscribeOn(Schedulers.io)
    .observeOn(AndroidSchedulers.mainThread());

并且我想要过滤输出，所以我尝试在上面添加一个 .filter() 操作符，但它似乎需要一个 Predicate> 而不仅仅是一个 MyClassA 对象，我可以用它检查并只允许 value2 == 10 的对象.

and I would like to have the output filtered, so I tried adding a .filter() operator to the above but it seems to require a Predicate<List<MyClassA>> instead of just a MyClassA object with which I can check and allow only ones where value2 == 10.

我对 RxJava 和 RxJava2 还很陌生，似乎我在这里遗漏了一些基本的东西?

I'm pretty new to RxJava and RxJava2 and seems like I'm missing something basic here?

TIA

推荐答案

您可以展开列表，然后收集通过过滤器的条目:

You can unroll the list and then collect up those entries that passed the filter:

apiService.getListObservable()
.subscribeOn(Schedulers.io)
.flatMapIterable(new Function<List<MyClassA>, List<MyClassA>>() {
    @Override public List<MyClassA> apply(List<MyClassA> v) {
        return v;
    }
})
.filter(new Predicate<MyClassA>() {
    @Override public boolean test(MyClassA v) {
        return v.value2 == 10;
    }
})
.toList()
.observeOn(AndroidSchedulers.mainThread())
.subscribe(...);

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