Android函数响应式编程——必学的RxJava组合操作符startWith、merge、concat、zip、combineLastest

1.startWith：给你被观察者的数据流前再增加一点同类型的数据，这里增加的是1,2

rx.Observable.just(3, 4, 5).startWith(1, 2)        .subscribe(new Action1() {            @Override            public void call(Integer integer) {                Log.i("xbh", integer + "");            }        });

输出

12-09 07:17:18.439 18450-18450/com.hdu.a15058124.homework3 I/xbh: 1
12-09 07:17:18.439 18450-18450/com.hdu.a15058124.homework3 I/xbh: 2
12-09 07:17:18.439 18450-18450/com.hdu.a15058124.homework3 I/xbh: 3
12-09 07:17:18.439 18450-18450/com.hdu.a15058124.homework3 I/xbh: 4
12-09 07:17:18.439 18450-18450/com.hdu.a15058124.homework3 I/xbh: 5

2.merge：把多个被观察者合并到一个被观察者身上一起输出，但是可能会让合并的被观察者发射的数据交错。

rx.Observable obs1 = rx.Observable.just(1,2,3).subscribeOn(Schedulers.io());rx.Observable obs2 = rx.Observable.just(4,5,6);rx.Observable.merge(obs1,obs2).subscribe(new Action1() {    @Override    public void call(Integer integer) {        Log.i("xbh", integer + "");    }});

输出

12-09 07:18:35.919 19718-19718/? I/xbh: 4
12-09 07:18:35.919 19718-19718/? I/xbh: 5
12-09 07:18:35.919 19718-19718/? I/xbh: 6
12-09 07:18:35.921 19718-19758/? I/xbh: 1
12-09 07:18:35.921 19718-19758/? I/xbh: 2
12-09 07:18:35.921 19718-19758/? I/xbh: 3

3.concat：也是合并数据，但是严格按照顺序发射，一个被观察者数据发送完前不会发送后一个被观察者的数据。

rx.Observable obs1 = rx.Observable.just(1,2,3).subscribeOn(Schedulers.io());rx.Observable obs2 = rx.Observable.just(4,5,6);rx.Observable.concat(obs1,obs2).subscribe(new Action1() {    @Override    public void call(Integer integer) {        Log.i("xbh", integer + "");    }});

12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 1
12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 2
12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 3
12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 4
12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 5
12-09 07:22:43.374 23503-23554/com.hdu.a15058124.homework3 I/xbh: 6

4.zip合并多个被观察者发出的数据项，但是如果一个被观察者的数据更多，多出来的那部分不会被发送。

rx.Observable obs1 = rx.Observable.just(1,2,3,4,5);rx.Observable obs2 = rx.Observable.just("a","b","c");rx.Observable.zip(obs1,obs2,new Func2,String,String>() {    @Override    public String call(Integer integer, String s) {        return integer + s;    }}).subscribe(new Action1() {    @Override    public void call(String s) {        Log.i("xbh", s);    }});

输出：

12-09 07:28:28.115 28857-28857/com.hdu.a15058124.homework3 I/xbh: 1a
12-09 07:28:28.115 28857-28857/com.hdu.a15058124.homework3 I/xbh: 2b
12-09 07:28:28.115 28857-28857/com.hdu.a15058124.homework3 I/xbh: 3c

5.combineLatest：把第一个被观察者最新的数据，和另外的观察者相连。

rx.Observable obs1 = rx.Observable.just(1,2,3,4,5,6,7,8,9);rx.Observable obs2 = rx.Observable.just("a","b","b");rx.Observable.combineLatest(obs1,obs2,new Func2,String,String>() {    @Override    public String call(Integer integer, String s) {        return integer + s;    }}).subscribe(new Action1() {    @Override    public void call(String s) {        Log.i("xbh", s);    }});

输出：

12-09 07:29:14.421 29655-29655/? I/xbh: 9a
12-09 07:29:14.421 29655-29655/? I/xbh: 9b
12-09 07:29:14.421 29655-29655/? I/xbh: 9b

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