5. Rxjava2 : 判断操作符

1. RxJava2 : 什么是观察者模式
2. RxJava2 : 创建操作符(无关时间)
3. Rxjava2 : 创建操作符(有关时间)
4. Rxjava2 : 变换操作符
5. Rxjava2 : 判断操作符
6. Rxjava2 : 筛选操作符
7. Rxjava2 : 合并操作符
8. Rxjava2 : do操作符
9. Rxjava2 : error处理
10. Rxjava2 : 重试
11. Rxjava2 : 线程切换

api	use
all	{{Observable.all}}
contains	{{Observable.contains}}
isEmpty	{{Observable.isEmpty}}
defaultIfEmpty	{{Observable.defaultIfEmpty}}
takeWhile / takeUntil	{{Observable.takeWhile}}

all

• 判断是否全部满足,只有全部满足的时候才会返回 true

Disposable subscribe = Observable.just(1, 2, 3)
                .all(new Predicate() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer>2;
                    }
                })
                .subscribe(aBoolean -> Log.d(TAG, "aBoolean:" + aBoolean));

log

02-11 16:33:45.936 10199-10199/... D/SplashActivity: aBoolean:false

contains

• 判断是否包含

 Disposable subscribe = Observable.just(1, 2, 3, 4, 5)
                .contains(1)
                .subscribe(aBoolean -> Log.d(TAG, "aBoolean:" + aBoolean));

log

02-11 17:28:06.486 15538-15538/... D/SplashActivity: aBoolean:true

isEmpty

• 判断是否为空

Disposable subscribe = Observable.just(1, 2, 3, 4, 5)
                .isEmpty()
                .subscribe(aBoolean -> Log.d(TAG, "aBoolean:" + aBoolean));

log

02-11 17:31:04.306 15894-15894/... D/SplashActivity: aBoolean:false

defaultIfEmpty

• 当什么也不发送直接发送 complete 的时候,给与一个默认值,如果只发送一个 onError 的话,则这个默认值不会起作用

Observable.create(new ObservableOnSubscribe() {
            @Override
            public void subscribe(ObservableEmitter e) throws Exception {
                e.onComplete();
            }
        })
                .defaultIfEmpty(1)
                .subscribe(new Observer() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

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

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

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

log

02-11 17:35:40.806 16324-16324/... D/SplashActivity: integer:1
02-11 17:35:40.806 16324-16324/... D/SplashActivity: onComplete

takeWhile

• takeWhile
  只发送满足条件的,但一旦碰到不满足的,后面的均不会发送,发送 complete 结束

• takeUntil
  一直发送,直到发送到满足条件的结束,并且,满足条件的那一个也会发送,之后发送complete 结束

//takeWhile 
Observable.just(1, 2, 3, 4, 5)
                .takeWhile(new Predicate() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer != 4;
                    }
                })
                .subscribe(new Observer() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

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

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

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

log

02-11 16:37:18.896 10620-10620/... D/SplashActivity: integer:1
02-11 16:37:18.896 10620-10620/... D/SplashActivity: integer:2
02-11 16:37:18.896 10620-10620/... D/SplashActivity: integer:3
02-11 16:37:18.896 10620-10620/... D/SplashActivity: onComplete

//takeUntil          
Observable.just(1, 2, 3, 4, 5, 6)
                .takeUntil(new Predicate() {
                    @Override
                    public boolean test(Integer integer) throws Exception {
                        return integer == 4;
                    }
                })
                .subscribe(new Observer() {
                    @Override
                    public void onSubscribe(Disposable d) {

                    }

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

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

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

log

02-11 17:03:11.396 12703-12703/... D/SplashActivity: integer:1
02-11 17:03:11.396 12703-12703/... D/SplashActivity: integer:2
02-11 17:03:11.396 12703-12703/... D/SplashActivity: integer:3
02-11 17:03:11.396 12703-12703/... D/SplashActivity: integer:4
02-11 17:03:11.396 12703-12703/... D/SplashActivity: onComplete