java.lang.Object
- hu.akarnokd.rxjava3.operators.ObservableTransformers

```
public final class ObservableTransformers
extends java.lang.Object
```
Additional operators in the form of ObservableTransformer, use Observable.compose(ObservableTransformer) to apply the operators to an existing sequence.

Since:

0.18.2

See Also:

Observables

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static <T,R> ObservableTransformer<T,R>`	`errorJump(ObservableTransformer<T,R> transformer)`	Allows an upstream error to jump over an inner transformation and is then reapplied once the inner transformation's returned Flowable terminates.
`static <T> ObservableTransformer<T,T>`	`filterAsync(Function<? super T,? extends ObservableSource<java.lang.Boolean>> asyncPredicate)`	Maps each upstream value into a single `true` or `false` value provided by a generated ObservableSource for that input value and emits the input value if the inner ObservableSource returned `true`.
`static <T> ObservableTransformer<T,T>`	`filterAsync(Function<? super T,? extends ObservableSource<java.lang.Boolean>> asyncPredicate, int bufferSize)`	Maps each upstream value into a single `true` or `false` value provided by a generated ObservableSource for that input value and emits the input value if the inner ObservableSource returned `true`.
`static <T,R> @NonNull ObservableTransformer<T,R>`	`flatMapDrop(Function<? super T,? extends ObservableSource<? extends R>> mapper)`	FlatMap only one `ObservableSource` at a time and ignore upstream values until it terminates.
`static <T,R> @NonNull ObservableTransformer<T,R>`	`flatMapLatest(Function<? super T,? extends ObservableSource<? extends R>> mapper)`	FlatMap only one `ObservableSource` at a time and keep the latest upstream value until it terminates and resume with the `ObservableSource` mapped for that latest upstream value.
`static <T> @NonNull ObservableTransformer<T,java.lang.Long>`	`indexOf(@NonNull Predicate<? super T> predicate)`	Returns the first index of an element that matches a predicate or -1L if no elements match.
`static <T,R> ObservableTransformer<T,R>`	`mapAsync(Function<? super T,? extends ObservableSource<? extends R>> mapper)`	Maps each upstream value into a single value provided by a generated ObservableSource for that input value, which is then emitted to the downstream.
`static <T,R> ObservableTransformer<T,R>`	`mapAsync(Function<? super T,? extends ObservableSource<? extends R>> mapper, int capacityHint)`	Maps each upstream value into a single value provided by a generated ObservableSource for that input value, which is then emitted to the downstream.
`static <T,U,R> ObservableTransformer<T,R>`	`mapAsync(Function<? super T,? extends ObservableSource<? extends U>> mapper, BiFunction<? super T,? super U,? extends R> combiner)`	Maps each upstream value into a single value provided by a generated ObservableSource for that input value and combines the original and generated single value into a final result item to be emitted to downstream.
`static <T,U,R> ObservableTransformer<T,R>`	`mapAsync(Function<? super T,? extends ObservableSource<? extends U>> mapper, BiFunction<? super T,? super U,? extends R> combiner, int capacityHint)`	Maps each upstream value into a single value provided by a generated ObservableSource for that input value and combines the original and generated single value into a final result item to be emitted to downstream.
`static <T> @NonNull ObservableTransformer<T,T>`	`observeOnDrop(@NonNull Scheduler scheduler)`	Schedules the event emission on a `Scheduler` and drops upstream values while the `onNext` with the current item is executing on that scheduler.
`static <T> @NonNull ObservableTransformer<T,T>`	`observeOnLatest(@NonNull Scheduler scheduler)`	Schedules the event emission on a `Scheduler` and keeps the latest upstream item while the downstream's `onNext` is executing so that it will resume with that latest value.
`static <T> ObservableTransformer<T,T>`	`valve(ObservableSource<java.lang.Boolean> other)`	Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source.
`static <T> ObservableTransformer<T,T>`	`valve(ObservableSource<java.lang.Boolean> other, boolean defaultOpen)`	Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source and starts with the specified valve state.
`static <T> ObservableTransformer<T,T>`	`valve(ObservableSource<java.lang.Boolean> other, boolean defaultOpen, int bufferSize)`	Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source and starts with the specified valve state and the specified buffer size hint.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - indexOf
```
@SchedulerSupport("none")
@CheckReturnValue
@NonNull
public static <T> @NonNull ObservableTransformer<T,java.lang.Long> indexOf(@NonNull
                                                                                 @NonNull Predicate<? super T> predicate)
```
    Returns the first index of an element that matches a predicate or -1L if no elements match.
    
    Type Parameters:
    
    T - the upstream element type
    
    Parameters:
    
    predicate - the predicate called to test each item, returning true will stop the sequence and return the current item index
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.18.2
  - observeOnDrop
```
@SchedulerSupport("custom")
@CheckReturnValue
@NonNull
public static <T> @NonNull ObservableTransformer<T,T> observeOnDrop(@NonNull
                                                                          @NonNull Scheduler scheduler)
```
    Schedules the event emission on a Scheduler and drops upstream values while the onNext with the current item is executing on that scheduler.
    Errors are delayed until all items that weren't dropped have been delivered.
    
    Type Parameters:
    
    T - the element type
    
    Parameters:
    
    scheduler - the scheduler to use for emitting events on
    
    Returns:
    
    the new ObservableTransformer instance
    
    See Also:
    
    observeOnLatest(Scheduler)
  - observeOnLatest
```
@SchedulerSupport("custom")
@CheckReturnValue
@NonNull
public static <T> @NonNull ObservableTransformer<T,T> observeOnLatest(@NonNull
                                                                            @NonNull Scheduler scheduler)
```
    Schedules the event emission on a Scheduler and keeps the latest upstream item while the downstream's onNext is executing so that it will resume with that latest value.
    Errors are delayed until the very last item has been delivered.
    
    Type Parameters:
    
    T - the element type
    
    Parameters:
    
    scheduler - the scheduler to use for emitting events on
    
    Returns:
    
    the new ObservableTransformer instance
    
    See Also:
    
    observeOnLatest(Scheduler)
  - flatMapDrop
```
@SchedulerSupport("none")
@CheckReturnValue
@NonNull
public static <T,R> @NonNull ObservableTransformer<T,R> flatMapDrop(Function<? super T,? extends ObservableSource<? extends R>> mapper)
```
    FlatMap only one ObservableSource at a time and ignore upstream values until it terminates.
    Errors are delayed until both the upstream and the active inner ObservableSource terminate.
    
    Type Parameters:
    
    T - the upstream value type
    
    R - the output type
    
    Parameters:
    
    mapper - the function that takes an upstream item and returns a ObservableSource to be run exclusively until it finishes
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.19.0
  - flatMapLatest
```
@SchedulerSupport("none")
@CheckReturnValue
@NonNull
public static <T,R> @NonNull ObservableTransformer<T,R> flatMapLatest(Function<? super T,? extends ObservableSource<? extends R>> mapper)
```
    FlatMap only one ObservableSource at a time and keep the latest upstream value until it terminates and resume with the ObservableSource mapped for that latest upstream value.
    Errors are delayed until both the upstream and the active inner ObservableSource terminate.
    
    Type Parameters:
    
    T - the upstream value type
    
    R - the output type
    
    Parameters:
    
    mapper - the function that takes an upstream item and returns a ObservableSource to be run exclusively until it finishes
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.19.0
  - errorJump
```
public static <T,R> ObservableTransformer<T,R> errorJump(ObservableTransformer<T,R> transformer)
```
    Allows an upstream error to jump over an inner transformation and is then reapplied once the inner transformation's returned Flowable terminates.
    
    Type Parameters:
    
    T - the upstream value type
    
    R - the downstream value type
    
    Parameters:
    
    transformer - the transformation applied to the flow on a per-Subscriber basis
    
    Returns:
    
    the new FlowableTransformer instance
    
    Since:
    
    0.19.1
  - valve
```
@SchedulerSupport("none")
public static <T> ObservableTransformer<T,T> valve(ObservableSource<java.lang.Boolean> other)
```
    Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source.
    Properties:
    
    The operator starts with an open valve.
    
    If the other ObservableSource completes, the sequence terminates with an IllegalStateException.
    
    The operator doesn't run on any particular Scheduler.
    
    The operator uses an internal unbounded buffer of size Flowable.bufferSize() to hold onto values if the valve is closed.
    Type Parameters:
    
    T - the value type of the main source
    
    Parameters:
    
    other - the other source
    
    Returns:
    
    the new ObservableTransformer instance
    
    Throws:
    
    java.lang.NullPointerException - if other is null
    
    Since:
    
    0.20.2
  - valve
```
@SchedulerSupport("none")
public static <T> ObservableTransformer<T,T> valve(ObservableSource<java.lang.Boolean> other,
                                                         boolean defaultOpen)
```
    Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source and starts with the specified valve state.
    Properties:
    
    If the other ObservableSource completes, the sequence terminates with an IllegalStateException.
    
    The operator doesn't run on any particular Scheduler.
    
    The operator uses an internal unbounded buffer of size Flowable.bufferSize() to hold onto values if the valve is closed.
    Type Parameters:
    
    T - the value type of the main source
    
    Parameters:
    
    other - the other source
    
    defaultOpen - should the valve start as open?
    
    Returns:
    
    the new ObservableTransformer instance
    
    Throws:
    
    java.lang.NullPointerException - if other is null
    
    Since:
    
    0.20.2
  - valve
```
@SchedulerSupport("none")
public static <T> ObservableTransformer<T,T> valve(ObservableSource<java.lang.Boolean> other,
                                                         boolean defaultOpen,
                                                         int bufferSize)
```
    Relays values until the other ObservableSource signals false and resumes if the other ObservableSource signals true again, like closing and opening a valve and not losing any items from the main source and starts with the specified valve state and the specified buffer size hint.
    Properties:
    
    If the other ObservableSource completes, the sequence terminates with an IllegalStateException.
    
    The operator doesn't run on any particular Scheduler.
    Type Parameters:
    
    T - the value type of the main source
    
    Parameters:
    
    other - the other source
    
    defaultOpen - should the valve start as open?
    
    bufferSize - the buffer size hint (the chunk size of the underlying unbounded buffer)
    
    Returns:
    
    the new ObservableTransformer instance
    
    Throws:
    
    java.lang.IllegalArgumentException - if bufferSize <= 0
    
    java.lang.NullPointerException - if other is null
    
    Since:
    
    0.20.2
  - mapAsync
```
public static <T,R> ObservableTransformer<T,R> mapAsync(Function<? super T,? extends ObservableSource<? extends R>> mapper)
```
    Maps each upstream value into a single value provided by a generated ObservableSource for that input value, which is then emitted to the downstream.
    Only the first item emitted by the inner ObservableSource are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input value type
    
    R - the result value type
    
    Parameters:
    
    mapper - the function that receives the upstream value and returns a ObservableSource that should emit a single value to be emitted.
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4
  - mapAsync
```
public static <T,R> ObservableTransformer<T,R> mapAsync(Function<? super T,? extends ObservableSource<? extends R>> mapper,
                                                                    int capacityHint)
```
    Maps each upstream value into a single value provided by a generated ObservableSource for that input value, which is then emitted to the downstream.
    Only the first item emitted by the inner ObservableSource are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input value type
    
    R - the result value type
    
    Parameters:
    
    mapper - the function that receives the upstream value and returns a ObservableSource that should emit a single value to be emitted.
    
    capacityHint - the number of items expected from the upstream to be buffered while each inner ObservableSource is executing.
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4
  - mapAsync
```
public static <T,U,R> ObservableTransformer<T,R> mapAsync(Function<? super T,? extends ObservableSource<? extends U>> mapper,
                                                                            BiFunction<? super T,? super U,? extends R> combiner)
```
    Maps each upstream value into a single value provided by a generated ObservableSource for that input value and combines the original and generated single value into a final result item to be emitted to downstream.
    Only the first item emitted by the inner ObservableSource are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input value type
    
    U - the intermediate value type
    
    R - the result value type
    
    Parameters:
    
    mapper - the function that receives the upstream value and returns a ObservableSource that should emit a single value to be emitted.
    
    combiner - the bi-function that receives the original upstream value and the single value emitted by the ObservableSource and returns a result value to be emitted to downstream.
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4
  - mapAsync
```
public static <T,U,R> ObservableTransformer<T,R> mapAsync(Function<? super T,? extends ObservableSource<? extends U>> mapper,
                                                                            BiFunction<? super T,? super U,? extends R> combiner,
                                                                            int capacityHint)
```
    Maps each upstream value into a single value provided by a generated ObservableSource for that input value and combines the original and generated single value into a final result item to be emitted to downstream.
    Only the first item emitted by the inner ObservableSource are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input value type
    
    U - the intermediate value type
    
    R - the result value type
    
    Parameters:
    
    mapper - the function that receives the upstream value and returns a ObservableSource that should emit a single value to be emitted.
    
    combiner - the bi-function that receives the original upstream value and the single value emitted by the ObservableSource and returns a result value to be emitted to downstream.
    
    capacityHint - the number of items expected from the upstream to be buffered while each inner ObservableSource is executing.
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4
  - filterAsync
```
public static <T> ObservableTransformer<T,T> filterAsync(Function<? super T,? extends ObservableSource<java.lang.Boolean>> asyncPredicate)
```
    Maps each upstream value into a single true or false value provided by a generated ObservableSource for that input value and emits the input value if the inner ObservableSource returned true.
    Only the first item emitted by the inner ObservableSource's are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input and output value type
    
    Parameters:
    
    asyncPredicate - the function that receives the upstream value and returns a ObservableSource that should emit a single true to indicate the original value should pass.
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4
  - filterAsync
```
public static <T> ObservableTransformer<T,T> filterAsync(Function<? super T,? extends ObservableSource<java.lang.Boolean>> asyncPredicate,
                                                               int bufferSize)
```
    Maps each upstream value into a single true or false value provided by a generated ObservableSource for that input value and emits the input value if the inner ObservableSource returned true.
    Only the first item emitted by the inner ObservableSource's are considered. If the inner ObservableSource is empty, no resulting item is generated for that input value.
    The inner ObservableSources are consumed in order and one at a time.
    
    Type Parameters:
    
    T - the input and output value type
    
    Parameters:
    
    asyncPredicate - the function that receives the upstream value and returns a ObservableSource that should emit a single true to indicate the original value should pass.
    
    bufferSize - the internal buffer size and prefetch amount to buffer items from upstream until their turn comes up
    
    Returns:
    
    the new ObservableTransformer instance
    
    Since:
    
    0.20.4

Class ObservableTransformers

Method Summary

Methods inherited from class java.lang.Object

Method Detail

indexOf

observeOnDrop

observeOnLatest

flatMapDrop

flatMapLatest

errorJump

valve

valve

valve

mapAsync

mapAsync

mapAsync

mapAsync

filterAsync

filterAsync