操作符之条件 / 布尔操作符 - Andy_Loong

1、作用

通过设置函数，判断被观察者（Observable）发送的事件是否符合条件

2、类型

3、详解

3.1 all（）----- 见rxdocs.pdf第192页

　　　　作用：判断发送的每项数据是否都满足设置的函数条件

    public static void all() {
        Observable.just(1, 2, 3, 4, 5, 10)
                .all(new Predicate<Integer>() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer >= 10;
                    }
                })
                .subscribe(new SingleObserver<Boolean>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onSuccess(Boolean value) {
                        Log.d(TAG, "onSuccess: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }
                });
    }

　　　　输出：

08-09 19:56:20.782  4775  4775 D Operation: onSubscribe
08-09 19:56:20.782  4775  4775 D Operation: onSuccess: value = false

3.2 takeWhile（）----- 见rxdocs.pdf第201页

　　　　作用：发射Observable发射的数据，直到一个指定的条件不成立

    public static void takeWhile() {
        Observable.just(1, 2, 3, 4, 5, 10)
                .takeWhile(new Predicate<Integer>() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer < 4;
                    }
                })
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onNext(Integer value) {
                        Log.d(TAG, "onNext: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });
    }

输出：

08-09 20:02:26.093  5131  5131 D Operation: onSubscribe
08-09 20:02:26.093  5131  5131 D Operation: onNext: value = 1
08-09 20:02:26.093  5131  5131 D Operation: onNext: value = 2
08-09 20:02:26.093  5131  5131 D Operation: onNext: value = 3
08-09 20:02:26.093  5131  5131 D Operation: onComplete

3.3 skipWhile（）----- 见rxdocs.pdf第198页

　　　　作用：丢弃Observable发射的数据，直到一个指定的条件不成立。即直到该判断条件 = false时，才开始发送Observable的数据。与takeWhile()相反。

    public static void skipWhile() {
        Observable.just(1, 2, 3, 4, 5, 10)
                .skipWhile(new Predicate<Integer>() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer < 4;
                    }
                }).subscribe(new Observer<Integer>() {
            @Override
            public void onSubscribe(Disposable d) {
                Log.d(TAG, "onSubscribe");
            }

            @Override
            public void onNext(Integer value) {
                Log.d(TAG, "onNext: value = " + value);
            }

            @Override
            public void onError(Throwable e) {
                Log.d(TAG, "onError: " + e.toString());
            }

            @Override
            public void onComplete() {
                Log.d(TAG, "onComplete");
            }
        });
    }

输出：

08-12 11:04:21.003 12582 12582 D Operation: onSubscribe
08-12 11:04:21.003 12582 12582 D Operation: onNext: value = 4
08-12 11:04:21.003 12582 12582 D Operation: onNext: value = 5
08-12 11:04:21.003 12582 12582 D Operation: onNext: value = 10
08-12 11:04:21.003 12582 12582 D Operation: onComplete

3.4 takeUtil（）----- 见rxdocs.pdf第199页

　　　　作用：执行到某个条件时，停止发送事件

    public static void takeUtil() {
        Observable.just(1, 2, 3, 4, 5, 10)
                .takeUntil(new Predicate<Integer>() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer > 4;
                    }
                }).subscribe(new Observer<Integer>() {
            @Override
            public void onSubscribe(Disposable d) {
                Log.d(TAG, "onSubscribe");
            }

            @Override
            public void onNext(Integer value) {
                Log.d(TAG, "onNext: value = " + value);
            }

            @Override
            public void onError(Throwable e) {
                Log.d(TAG, "onError: " + e.toString());
            }

            @Override
            public void onComplete() {
                Log.d(TAG, "onComplete");
            }
        });
    }

输出：

08-12 11:10:31.067 12856 12856 D Operation: onSubscribe
08-12 11:10:31.067 12856 12856 D Operation: onNext: value = 1
08-12 11:10:31.067 12856 12856 D Operation: onNext: value = 2
08-12 11:10:31.067 12856 12856 D Operation: onNext: value = 3
08-12 11:10:31.067 12856 12856 D Operation: onNext: value = 4
08-12 11:10:31.067 12856 12856 D Operation: onNext: value = 5
08-12 11:10:31.067 12856 12856 D Operation: onComplete

3.5 skipUtil（）----- 见rxdocs.pdf第198页

　　　　作用：丢弃原始Observable发射的数据，直到第二个Observable发射了一项数据

    public static void skipUtil() {
        Observable.interval(1, TimeUnit.SECONDS)
                .skipUntil(Observable.timer(5, TimeUnit.SECONDS))
                .subscribe(new Observer<Long>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onNext(Long value) {
                        Log.d(TAG, "onNext: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });

    }

输出：

08-12 11:18:39.298 13159 13159 D Operation: onSubscribe
08-12 11:18:45.303 13159 13184 D Operation: onNext: value = 5
08-12 11:18:46.302 13159 13184 D Operation: onNext: value = 6
08-12 11:18:47.303 13159 13184 D Operation: onNext: value = 7

3.6 sequenceEqual（）----- 见rxdocs.pdf第196页

　　　　作用：传递两个Observable给SequenceEqual操作符，它会比较两个Observable的发射物，如果两个序列是相同的（相同的数据，相同的顺序，相同的终止状态），它就发射true，否则发射false。

    public static void sequenceEqual() {
        Observable.sequenceEqual(Observable.just(1, 2, 3), Observable.just(1, 2, 3))
                .subscribe(new SingleObserver<Boolean>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onSuccess(Boolean value) {
                        Log.d(TAG, "onSuccess: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }
                });
    }

输出：

08-12 11:24:11.229 13438 13438 D Operation: onSubscribe
08-12 11:24:11.230 13438 13438 D Operation: onSuccess: value = true

3.7 contains（）----- 见rxdocs.pdf第194页

　　　　作用：判断发送的数据中是否包含指定数据

    public static void contains() {
        Observable.just(1, 2, 3, 4)
                .contains(2)
                .subscribe(new SingleObserver<Boolean>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onSuccess(Boolean value) {
                        Log.d(TAG, "onSuccess: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }
                });
    }

输出：

08-12 11:28:58.716 13670 13670 D Operation: onSubscribe
08-12 11:28:58.716 13670 13670 D Operation: onSuccess: value = true

3.8 isEmpty（）----- 见rxdocs.pdf第195页

　　　　作用：判断发送的数据是否为空

    public static void isEmpty() {
        Observable.empty()
                .isEmpty()
                .subscribe(new SingleObserver<Boolean>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onSuccess(Boolean value) {
                        Log.d(TAG, "onSuccess: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }
                });
    }

输出：

08-12 11:32:22.533 13892 13892 D Operation: onSubscribe
08-12 11:32:22.533 13892 13892 D Operation: onSuccess: value = true

3.9 amb（）----- 见rxdocs.pdf第193页

　　　　作用：当需要发送多个 Observable时，只发送先发送数据的Observable的数据，而其余 Observable则被丢弃。

    public static void amb() {
        Observable.ambArray(Observable.just(1, 2, 3).delay(1, TimeUnit.SECONDS)
                , Observable.just(7, 8, 9).delay(999, TimeUnit.MILLISECONDS))
                .subscribe(new Observer<Integer>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onNext(Integer value) {
                        Log.d(TAG, "onNext: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });
    }

输出：

08-12 11:38:43.328 14136 14136 D Operation: onSubscribe
08-12 11:38:44.330 14136 14161 D Operation: onNext: value = 7
08-12 11:38:44.330 14136 14161 D Operation: onNext: value = 8
08-12 11:38:44.330 14136 14161 D Operation: onNext: value = 9
08-12 11:38:44.331 14136 14161 D Operation: onComplete

3.10 defaultIfEmpty（）----- 见rxdocs.pdf第196页

　　　　作用：在不发送任何有效事件（ Next事件）、仅发送了 Complete 事件的前提下，发送一个默认值

    public static void defaultIfEmpty() {
        Observable.empty()
                .defaultIfEmpty("Andy")
                .subscribe(new Observer<Object>() {
                    @Override
                    public void onSubscribe(Disposable d) {
                        Log.d(TAG, "onSubscribe");
                    }

                    @Override
                    public void onNext(Object value) {
                        Log.d(TAG, "onNext: value = " + value);
                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.d(TAG, "onError: " + e.toString());
                    }

                    @Override
                    public void onComplete() {
                        Log.d(TAG, "onComplete");
                    }
                });
    }

输出：

08-12 11:48:24.847 14642 14642 D Operation: onSubscribe
08-12 11:48:24.847 14642 14642 D Operation: onNext: value = Andy
08-12 11:48:24.847 14642 14642 D Operation: onComplete

4、总结

发表于 2019-08-09 20:03 Andy_Loong 阅读(253) 评论(0) 编辑收藏举报