一、算術和聚合操作符列表

1.1 算術操作符RXjava-math:

這個模組需要導下面這個包,不支援Rxjava2，所以Rxjava2用不了噢：

    compile 'io.reactivex:rxjava-math:1.0.0'

1.2 其他聚合操作符:

ps: 由於這些操作必須等待資料發射完成（通常也必須快取這些資料），它們對於非常長或者無限的序列來說是危險的，不推薦使用。

二、聚合操作符

2.1 concat() / concatArray

順序連線多個Observables。

    /**
     * 順序連線多個Observables
     */
    private void testConcat() {
        Observable.concat(Observable.just(Observable.just("1"),Observable.just("2")))
                .subscribe(new Consumer<String>() {
                    @Override
                    public void accept(@NonNull String s) throws Exception {
                        Log.e(TAG, "accept: "+s);
                    }
                });


        Observable.concat(Observable.just("3","4"),Observable.just("5","6"))
                .subscribe(new Consumer<String>() {
                    @Override
                    public void accept(@NonNull String s) throws Exception {
                        Log.e(TAG, "accept: "+s);
                    }
                });

    }

輸出內容為:

03-02 19:13:01.275 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 1
03-02 19:13:01.275 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 2
03-02 19:13:01.277 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 3
03-02 19:13:01.277 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 4
03-02 19:13:01.277 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 5
03-02 19:13:01.277 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 6

2.2 count()操作符

計算資料項的個數。返回 long型別

    private void testCount() {

        Observable.just("1", "2")
                .count()
                .subscribe(new Consumer<Long>() {
                    @Override
                    public void accept(@NonNull Long aLong) throws Exception {
                        Log.e(TAG, "accept: "+aLong);

                    }
                });

    }

輸出:

03-02 19:13:01.275 29166-29166/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 2

2.3 reduce()操作符

第一次獲取到前兩個資料，之後每次獲取到的資料是返回的資料+原始的下一個資料。最後返回到觀察者

        Observable.just("1","2","3","4")
                .reduce(new BiFunction<String, String, String>() {
                    @Override
                    public String apply(@NonNull String s, @NonNull String s2) throws Exception {
                        Log.e(TAG, "apply: "+s +" "+ s2);

                        return "返回值";
                    }
                }).subscribe(new Consumer<String>() {
                    @Override
                    public void accept(@NonNull String s) throws Exception {
                        Log.e(TAG, "accept: "+s);

                    }
                });

輸出為:

03-02 19:27:14.758 2983-2983/cn.com.minstone.rxjavalearn E/[email protected]@: apply: 1 2
03-02 19:27:14.758 2983-2983/cn.com.minstone.rxjavalearn E/[email protected]@: apply: 返回值 3
03-02 19:27:14.758 2983-2983/cn.com.minstone.rxjavalearn E/[email protected]@: apply: 返回值 4
03-02 19:27:14.758 2983-2983/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 返回值

2.4 collect()操作符

和reduce類似，但是collect可以變型別。

    private void testCollect() {

        Observable.just("1","2","3","4")
                .collect(new Callable<Integer>() {
                    @Override
                    public Integer call() throws Exception {
                        return 6;
                    }
                }, new BiConsumer<Integer, String>() {
                    @Override
                    public void accept(@NonNull Integer integer, @NonNull String s) throws Exception {
                        Log.e(TAG, "accept: "+integer+" "+ s);
                    }
                })
                .subscribe(new Consumer<Integer>() {
                    @Override
                    public void accept(@NonNull Integer integer) throws Exception {
                        Log.e(TAG, "accept2: "+integer);

                    }
                });



    }

輸出的內容為:

03-02 19:34:23.382 5108-5108/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 6 1
03-02 19:34:23.382 5108-5108/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 6 2
03-02 19:34:23.383 5108-5108/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 6 3
03-02 19:34:23.383 5108-5108/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 6 4
03-02 19:34:23.383 5108-5108/cn.com.minstone.rxjavalearn E/[email protected]@: accept2: 6

2.5 toList / toSortedList()操作符

收集原始Observable發射的所有資料到一個列表，然後返回這個列表

    private void testToList() {

        Observable.just("1","2","3","4")
                .toList()
                .subscribe(new Consumer<List<String>>() {
                    @Override
                    public void accept(@NonNull List<String> strings) throws Exception {
                        for(String str:strings){
                            Log.e(TAG, "accept: "+str);
                        }
                    }
                });
    }

輸出結果為:

03-02 19:40:06.437 7578-7578/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 1
03-02 19:40:06.437 7578-7578/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 2
03-02 19:40:06.437 7578-7578/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 3
03-02 19:40:06.437 7578-7578/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 4

2.7 ToSortedList()操作符

和toList基本一致，但是ToSortedList可以自定義排序:

    private void testToSortedList() {

        Observable.just(1,2,3,4)
                .toSortedList(new TestComparator())
                .subscribe(new Consumer<List<Integer>>() {
                    @Override
                    public void accept(@NonNull List<Integer> integers) throws Exception {
                        for(Integer str:integers){
                            Log.e(TAG, "accept: "+str);
                        }
                    }
                });
    }

    public class TestComparator implements Comparator<Integer> {
        public int compare(Integer o1, Integer o2) {
            return o2- o1;
        }
    }

輸出的內容就為倒序啦:

03-02 19:47:39.637 10924-10924/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 4
03-02 19:47:39.637 10924-10924/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 3
03-02 19:47:39.637 10924-10924/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 2
03-02 19:47:39.637 10924-10924/cn.com.minstone.rxjavalearn E/[email protected]@: accept: 1

2.6 toMap / toMultiMap()操作符

和tolist思路差不多，toMap將序列資料轉換為一個Map，Map的key是根據一個函式計算的

    private void testToMap() {

        Observable.just(1,2,3,4)
                .toMap(new Function<Integer, String>() {
                    @Override
                    public String apply(@NonNull Integer integer) throws Exception {
                        //計算返回每個資料對應的key,這裡設定key為他本身
                        return integer+"";
                    }
                })
                .subscribe(new Consumer<Map<String, Integer>>() {
                    @Override
                    public void accept(@NonNull Map<String, Integer> map) throws Exception {
                        for (String key : map.keySet()) {
                            Log.e(TAG,"key= "+ key + ",value= " + map.get(key));
                        }


                    }
                });
    }

輸出內容為:

03-02 19:52:18.471 12321-12321/cn.com.minstone.rxjavalearn E/[email protected]@: key= 4,value= 4
03-02 19:52:18.471 12321-12321/cn.com.minstone.rxjavalearn E/[email protected]@: key= 1,value= 1
03-02 19:52:18.471 12321-12321/cn.com.minstone.rxjavalearn E/[email protected]@: key= 2,value= 2
03-02 19:52:18.471 12321-12321/cn.com.minstone.rxjavalearn E/[email protected]@: key= 3,value= 3

toMultimap和tomap不同的是，toMultimap處理之後的mao的value為Collection列表