android - How to create an Observable based on an existing function or function callback in RxJava?

Question

In the process of using Rxjava, there may already be many function callbacks, so how to create a data stream based on the parameters of these function callbacks?
For example, if I need to modify onKeyDown(), how can I process a specific sequence of user input according to the different keystrokes, such as special processing when the user inputs "1, 2, 3, 4".

Or if there are other function callbacks, how to use operators such as bufferDebouncezip to process the data of these function callbacks?

Answer 1

You can write like this

    private BehaviorSubject<Integer> bs;

    private void testSeri() {
        bs = BehaviorSubject.create();
        //每3次 accept 一次
        bs.buffer(3)
                .subscribe(new Consumer<List<Integer>>() {
                    @Override
                    public void accept(@NonNull List<Integer> ints) throws Exception {
                        StringBuilder sb = new StringBuilder();
                        for (int i = 0; i < ints.size(); i++){
                            sb.append(ints.get(0));
                        }
                        Toast.makeText(TestSubjectActivity.this, sb.toString(), Toast.LENGTH_SHORT).show();
                    }
                });
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        bs.onNext(keyCode);
        return super.onKeyDown(keyCode, event);
    }

onKeyDown is the callback of Activity. It is inconvenient to wrap it in another layer, so we use Subject, which can transmit data [anytime and anywhere], subscribe and transmit easily and write separately. For general callbacks, you can write it like this. Let me give you a feel for the callbacks positioned by Baidu

    class LocationObservable implements ObservableOnSubscribe<BDLocation> {
        @Override
        public void subscribe(final ObservableEmitter<BDLocation> e) throws Exception {

            initLocation();
            mLocationClient.registerLocationListener( new BDLocationListener(){
                @Override
                public void onReceiveLocation(BDLocation location) {
                    if (location != null) {
                        mLocationClient.stop();
                        if (!TextUtils.isEmpty(location.getCity())) {
                              e.onNext(location);
                              e.onComplete();
                        }
                    } else {
                        // 定位失败
                        e.onError(new Exception("百度地图 定位失败"));
                    }
                }
            } );
            mLocationClient.start();
        }
    }

For general functions, you can do this

Observable<String> o1 = Observable.fromCallable(new Callable<String>() {
            @Override
            public String call() {
                return func1();
            }
        });
        
        
public String func1(){
    return "ok";
}