Conditional and Boolean Operators

本文的主题为处理 Observable 的条件和布尔操作符。

这里的 Observable 实质上是可观察的数据流。

RxJava操作符（七）Conditional and Boolean

公共代码

fun <T> Observable<T>.dump() =

    this.subscribe({ println("onNext: $it") },

        { println("onError: $it: ${it.message}") },

        { println("onComplete") })

fun <T> Single<T>.dump() =

    this.subscribe({ println("onNext: $it") },

        { println("onError: $it: ${it.message}") })

All

ReactiveX - All operator

Reactive Extensions再入門 その１９「AnyメソッドとAllメソッド」

All 检查一个数据流的所有数据是否都满足某个条件。

  • RxNET
var subject = new Subject<int>();

subject.Subscribe(Console.WriteLine, () => Console.WriteLine("Subject completed"));

var all = subject.All(i => i < 5);

all.Subscribe(b => Console.WriteLine("All values less than 5? {0}", b));

subject.OnNext(1);

subject.OnNext(2);

subject.OnNext(6);

subject.OnNext(2);

subject.OnNext(1);

subject.OnCompleted();

/*

1

2

6

All values less than 5? False

2

1

Subject completed

*/
  • RxJava
val values = Observable.create<Int> { o ->

    o.onNext(0)

    o.onNext(10)

    o.onNext(10)

    o.onNext(2)

    o.onComplete()

}

values

    .all { i -> i % 2 == 0 }

    .dump()

/*

onSuccess: true

*/


val values = Observable.interval(150, TimeUnit.MILLISECONDS).take(5)

val subscription = values

    .all { i -> i < 3 }

    .dump()

val subscription2 = values

    .dump()

readLine()

subscription.dispose()

subscription2.dispose()

/*

onNext: 0

onNext: 1

onNext: 2

onNext: 3

onSuccess: false

onNext: 4

onComplete

*/


val values = Observable.create<Int> { o ->

    o.onNext(0)

    o.onNext(2)

    o.onError(Exception())

}

values

    .all { i -> i % 2 == 0 }

    .dump()

/*

onError: java.lang.Exception: null

*/
  • RxJS

RxJs - every

learn-rxjs - every

Amb

ReactiveX - Amb operator

Reactive Extensions再入門 その４１「どんどん合成するよ」

给定两个或多个数据流，Amb 只发送最早发送数据的数据流的所有数据。

  • RxNET
/*

    s1 -1--1--|

    s2 --2--2--|

    s3 ---3--3--|

    r  -1--1--|

*/

var s1 = new Subject<int>();

var s2 = new Subject<int>();

var s3 = new Subject<int>();

var result = Observable.Amb(s1, s2, s3);

result.Subscribe(

Console.WriteLine,

() => Console.WriteLine("Completed"));

s1.OnNext(1);

s2.OnNext(2);

s3.OnNext(3);

s1.OnNext(1);

s2.OnNext(2);

s3.OnNext(3);

s1.OnCompleted();

s2.OnCompleted();

s3.OnCompleted();

/*

1

1

Completed

*/


/*

    s1 ---1--|

    s2 -2--2--|

    s3 --3--3--|

    r  -2--2--|

*/

var s1 = new Subject<int>();

var s2 = new Subject<int>();

var s3 = new Subject<int>();

var result = Observable.Amb(s1, s2, s3);

result.Subscribe(

Console.WriteLine,

() => Console.WriteLine("Completed"));

// s1.OnNext(1);

s2.OnNext(2);

s3.OnNext(3);

s1.OnNext(1);

s2.OnNext(2);

s3.OnNext(3);

s1.OnCompleted();

s2.OnCompleted();

s3.OnCompleted();

/*

2

2

Completed

*/
  • RxJava





Observable.amb(listOf(

    Observable.timer(100, TimeUnit.MILLISECONDS).map { i -> "First" },

    Observable.timer(50, TimeUnit.MILLISECONDS).map { i -> "Second" },

    Observable.timer(70, TimeUnit.MILLISECONDS).map { i -> "Third" }))

    .dump()

/*

onNext: Second

onComplete

*/


Observable.ambArray(

    Observable.timer(100, TimeUnit.MILLISECONDS).map { i -> "First" },

    Observable.timer(50, TimeUnit.MILLISECONDS).map { i -> "Second" },

    Observable.timer(70, TimeUnit.MILLISECONDS).map { i -> "Third" })

    .dump()

/*

onNext: Second

onComplete

*/


Observable.timer(100, TimeUnit.MILLISECONDS).map { i -> "First" }

    .ambWith(Observable.timer(50, TimeUnit.MILLISECONDS).map { i -> "Second" })

    .ambWith(Observable.timer(70, TimeUnit.MILLISECONDS).map { i -> "Third" })

    .dump()

/*

onNext: Second

onComplete

*/
  • RxJS

RxJs - race

learn-rxjs - race

Contains / Any / Exists / IsEmpty

ReactiveX - Contains operator

Reactive Extensions再入門 その１９「AnyメソッドとAllメソッド」

Contains 检查一个数据流是否发送了某个特定数据。

Any / Exists 检查一个数据流是否发送了（满足特定条件的）数据。

IsEmpty 检查一个数据流是否没有发送任何数据。



  • RxNET
var subject = new Subject<int>();

subject.Subscribe(

Console.WriteLine,

() => Console.WriteLine("Subject completed"));

var contains = subject.Contains(2);

contains.Subscribe(

b => Console.WriteLine("Contains the value 2? {0}", b),

() => Console.WriteLine("contains completed"));

subject.OnNext(1);

subject.OnNext(2);

subject.OnNext(3);

subject.OnCompleted();

/*

1

2

Contains the value 2? True

contains completed

3

Subject completed

*/


var subject = new Subject<int>();

subject.Subscribe(Console.WriteLine, () => Console.WriteLine("Subject completed"));

var any = subject.Any();

any.Subscribe(b => Console.WriteLine("The subject has any values? {0}", b));

subject.OnNext(1);

subject.OnCompleted();

/*

1

The subject has any values? True

Subject completed

*/
  • RxJava
  • exists 已经改名为 any

val values = Observable.interval(100, TimeUnit.MILLISECONDS)

values

    .contains(4L)

    .dump()

/*

onSuccess: true

*/


val values = Observable.range(0, 2)

values

    .any { i -> i > 2 }

    .dump()

/*

onSuccess: false

*/


val values = Observable.range(0, 2)

values

    .any { i -> i > 2 }

    .dump()

/*

onSuccess: false

*/


val values = Observable.timer(1000, TimeUnit.MILLISECONDS)

values

    .isEmpty

    .dump()

/*

onSuccess: false

*/

DefaultIfEmpty

ReactiveX - DefaultIfEmpty operator

DefaultIfEmpty 发送源数据流的所有数据，当源数据流没有数据时发送缺省的某个数据。

  • RxNET
var subject = new Subject<int>();

subject.Subscribe(

Console.WriteLine,

() => Console.WriteLine("Subject completed"));

var defaultIfEmpty = subject.DefaultIfEmpty();

defaultIfEmpty.Subscribe(

b => Console.WriteLine("defaultIfEmpty value: {0}", b),

() => Console.WriteLine("defaultIfEmpty completed"));

subject.OnNext(1);

subject.OnNext(2);

subject.OnNext(3);

subject.OnCompleted();

/*

1

defaultIfEmpty value: 1

2

defaultIfEmpty value: 2

3

defaultIfEmpty value: 3

Subject completed

defaultIfEmpty completed

*/


var subject = new Subject<int>();

subject.Subscribe(

Console.WriteLine,

() => Console.WriteLine("Subject completed"));

var defaultIfEmpty = subject.DefaultIfEmpty();

defaultIfEmpty.Subscribe(

b => Console.WriteLine("defaultIfEmpty value: {0}", b),

() => Console.WriteLine("defaultIfEmpty completed"));

var default42IfEmpty = subject.DefaultIfEmpty(42);

default42IfEmpty.Subscribe(

b => Console.WriteLine("default42IfEmpty value: {0}", b),

() => Console.WriteLine("default42IfEmpty completed"));

subject.OnCompleted();

/*

Subject completed

defaultIfEmpty value: 0

defaultIfEmpty completed

default42IfEmpty value: 42

default42IfEmpty completed

*/
  • RxJava
val values = Observable.empty<Int>()

values

    .defaultIfEmpty(2)

    .dump()

/*

onNext: 2

onComplete

*/


val values = Observable.error<Int>(Exception())

values

    .defaultIfEmpty(2)

    .dump()

/*

onError: java.lang.Exception: null

*/

SequenceEqual

ReactiveX - SequenceEqual operator

SequenceEqual 判断两个数据流是否发送完全相同的数据。

  • RxNET
var subject1 = new Subject<int>();

subject1.Subscribe(

i => Console.WriteLine("subject1.OnNext({0})", i),

() => Console.WriteLine("subject1 completed"));

var subject2 = new Subject<int>();

subject2.Subscribe(

i => Console.WriteLine("subject2.OnNext({0})", i),

() => Console.WriteLine("subject2 completed"));

var areEqual = subject1.SequenceEqual(subject2);

areEqual.Subscribe(

i => Console.WriteLine("areEqual.OnNext({0})", i),

() => Console.WriteLine("areEqual completed"));

subject1.OnNext(1);

subject1.OnNext(2);

subject2.OnNext(1);

subject2.OnNext(2);

subject2.OnNext(3);

subject1.OnNext(3);

subject1.OnCompleted();

subject2.OnCompleted();

/*

subject1.OnNext(1)

subject1.OnNext(2)

subject2.OnNext(1)

subject2.OnNext(2)

subject2.OnNext(3)

subject1.OnNext(3)

subject1 completed

subject2 completed

areEqual.OnNext(True)

areEqual completed

*/
  • RxJava
val strings = Observable.just("1", "2", "3")

val ints = Observable.just(1, 2, 3)

Observable.sequenceEqual(strings, ints, BiPredicate { s, i -> s == i.toString() } )

    .dump()

/*

onSuccess: true

*/


val strings = Observable.just("1", "2", "3")

val ints = Observable.just(1, 2, 3)

Observable.sequenceEqual(strings, ints)

    .dump()

/*

onSuccess: false

*/


val values = Observable.create<Int> { o ->

    o.onNext(1)

    o.onNext(2)

    o.onError(Exception())

}

Observable.sequenceEqual(values, values)

    .dump()

/*

onError: java.lang.Exception: null

*/

SkipUntil

ReactiveX - SkipUntil operator

Reactive Extensions再入門 その８「SkipとTakeメソッド」

SkipUntil 忽略源数据流的数据，直到另一个数据流开始发送数据后才开始发送源数据流的数据。

  • RxNET
var subject = new Subject<int>();

var otherSubject = new Subject<Unit>();

subject

.SkipUntil(otherSubject)

.Subscribe(Console.WriteLine, () => Console.WriteLine("Completed"));

subject.OnNext(1);

subject.OnNext(2);

subject.OnNext(3);

otherSubject.OnNext(Unit.Default);

subject.OnNext(4);

subject.OnNext(5);

subject.OnNext(6);

subject.OnNext(7);

subject.OnNext(8);

subject.OnCompleted();

/*

4

5

6

7

8

Completed

*/
  • RxJava
val values = Observable.interval(100, TimeUnit.MILLISECONDS)

val cutoff = Observable.timer(250, TimeUnit.MILLISECONDS)

val subscription = values

    .skipUntil(cutoff)

    .dump()

readLine()

subscription.dispose()

/*

onNext: 2

onNext: 3

onNext: 4

...

*/
  • RxSwift
let disposeBag = DisposeBag()

Observable.of(1, 2, 3, 4, 5, 6)

    .takeWhile { $0 < 4 }

    .subscribe(onNext: { print($0) })

    .disposed(by: disposeBag)

/*

1

2

3

*/

SkipWhile

ReactiveX - SkipWhile operator

Reactive Extensions再入門 その８「SkipとTakeメソッド」

SkipWhile 忽略源数据流的数据，直到某个条件不再满足时才开始发送源数据流的数据。

  • RxNET
var subject = new Subject<int>();

subject

.SkipWhile(i => i < 4)

.Subscribe(Console.WriteLine, () => Console.WriteLine("Completed"));

subject.OnNext(1);

subject.OnNext(2);

subject.OnNext(3);

subject.OnNext(4);

subject.OnNext(3);

subject.OnNext(2);

subject.OnNext(1);

subject.OnNext(0);

subject.OnCompleted();

/*

4

3

2

1

0

Completed

*/
  • RxJava
val values = Observable.interval(100, TimeUnit.MILLISECONDS)

val subscription = values

    .skipWhile { v -> v < 2 }

    .dump()

readLine()

subscription.dispose()

/*

onNext: 2

onNext: 3

onNext: 4

...

*/
  • RxSwift
let disposeBag = DisposeBag()

Observable.of(1, 2, 3, 4, 5, 6)

    .skipWhile { $0 < 4 }

    .subscribe(onNext: { print($0) })

    .disposed(by: disposeBag)

/*

4

5

6

*/


let disposeBag = DisposeBag()

Observable.of("												


											
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