操做符之條件 / 布爾操做符

時間 2019-11-09

標籤條件布爾简体版

原文原文鏈接

一、做用

經過設置函數，判斷被觀察者（Observable）發送的事件是否符合條件

二、類型

三、詳解

3.1 all（）----- 見rxdocs.pdf第192頁ide

　　　　做用：判斷髮送的每項數據是否都知足設置的函數條件函數

    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());
                    }
                });
    }

　　　　輸出：spa

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（）----- 見rxdocs.pdf第201頁3d

　　　　做用：發射Observable發射的數據，直到一個指定的條件不成立code

    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");
                    }
                });
    }

輸出：server

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（）----- 見rxdocs.pdf第198頁blog

　　　　做用：丟棄Observable發射的數據，直到一個指定的條件不成立。即直到該判斷條件 = false時，纔開始發送Observable的數據。與takeWhile()相反。事件

    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");
            }
        });
    }

輸出：ip

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（）----- 見rxdocs.pdf第199頁it

　　　　做用：執行到某個條件時，中止發送事件

    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");
            }
        });
    }

輸出：

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（）----- 見rxdocs.pdf第198頁

　　　　做用：丟棄原始Observable發射的數據，直到第二個Observable發射了一項數據

    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");
                    }
                });

    }

輸出：

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（）----- 見rxdocs.pdf第196頁

　　　　做用：傳遞兩個Observable給SequenceEqual操做符，它會比較兩個Observable的發射物，若是兩個序列是相同的（相同的數據，相同的順序，相同的終止狀態），它就發射true，不然發射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());
                    }
                });
    }

輸出：

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（）----- 見rxdocs.pdf第194頁

　　　　做用：判斷髮送的數據中是否包含指定數據

    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());
                    }
                });
    }

輸出：

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（）----- 見rxdocs.pdf第195頁

　　　　做用：判斷髮送的數據是否爲空

    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());
                    }
                });
    }

輸出：

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（）----- 見rxdocs.pdf第193頁

　　　　做用：當須要發送多個 Observable時，只發送先發送數據的Observable的數據，而其他 Observable則被丟棄。

    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");
                    }
                });
    }

輸出：

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（）----- 見rxdocs.pdf第196頁

　　　　做用：在不發送任何有效事件（ Next事件）、僅發送了 Complete 事件的前提下，發送一個默認值

    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");
                    }
                });
    }

輸出：

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

四、總結

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