Question

我想将两个可观察变量names和nums组合成一个Student类-一种反映这些可观察变量的最新状态的模式。

这两个可观察物都在发射，并且onNext始终打印为nums和names。

但是，只有将combineLatest emits观察对象放在第一位，观察对象才从nums返回。

public class RxTrial1 {
    public static class Student{
        public String name;
        public long roll;
        public Student(String name, long roll) {
            super();
            this.name = name;
            this.roll = roll;
        }
        @Override
        public String toString() {
            return "Student [" + (name != null ? "name=" + name + ", " : "") + "roll=" + roll + "]";
        }
    }


    public static void main(String[] args) {

        Observable<String> strs = Observable.just("a", "b", "c").repeat();
        ConnectableObservable<Long> nums = Observable.interval(1, TimeUnit.SECONDS)
                                                .doOnNext( n -> System.out.println( "nums: " + n ) )
                                                .publish(); 

        Observable<String> names = nums
                                    .zipWith(strs, (n, s)->{ return s+n; })
                                    .doOnNext( s -> System.out.println( "names: " + s ) );

        Observable.combineLatest(nums, names, (s, n)->{ return new Student(n,s); })
            .subscribeOn(Schedulers.newThread())
            .doOnNext( st -> System.out.println( "combined: " + st ) )
            .subscribe( st -> System.out.println( "Student: " + st ) );




        nums.connect();


        wait10();
    }

    private static void wait10() {
        System.out.println("Start waiting");
        try {
            Thread.sleep(10_000l);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Done waiting");
    }
}

为什么仅将nums放在第一位会发光？

首先与nums配合良好：

Start waiting
nums: 0
names: a0
combined: Student [name=a0, roll=0]
Student: Student [name=a0, roll=0]
nums: 1
combined: Student [name=a0, roll=1]
Student: Student [name=a0, roll=1]
names: b1
combined: Student [name=b1, roll=1]
Student: Student [name=b1, roll=1]
nums: 2
combined: Student [name=b1, roll=2]
Student: Student [name=b1, roll=2]
names: c2
combined: Student [name=c2, roll=2]
Student: Student [name=c2, roll=2]
...

首先与names保持安静：

Start waiting
nums: 0
names: a0
nums: 1
names: b1
nums: 2
names: c2
nums: 3
names: a3
...

注意：

仅当我为组合的可观察项放置了subscribeOn时，它才有效。否则，它会在几分钟内进入OutOfMemory。
即使先输入名称，如果我都将take（10）放在两者上，它也可以正常工作。

RxJava CombineLatest的行为根据顺序而有所不同

0 个答案: