api_livedata/com.tomtom.tools.android.api.livedata/CombinedCollectionLiveData

CombinedCollectionLiveData

open class CombinedCollectionLiveData<I, O>(calculateValue: (List<I>) -> O) : MutableLiveData<O>

Similar to MediatorLiveData, but with a few key differences:

There's a single function to update the value when any of the sources change.
Updating multiple sources simultaneously only results in a single value update.

Consistent with kotlinx.coroutines.flow.combine, calculateValue will only be called when all added sources have a value set (even if that value is null). Until then, the returned LiveData's value will be unset and observers will not receive callbacks.

Parameters

I

The type of the input. I.e., the source LiveData values.

O

The type of the output LiveData value.

calculateValue

A method that calculates the value for this LiveData after one or more sources are updated.

Constructors

CombinedCollectionLiveData

constructor(calculateValue: (List<I>) -> O)

Inherited properties

val <T> LiveData<T>.observedValue: T?

Same as LiveData.getValue, except this variant throws a IllegalStateException when the LiveData instance does not have an active observer.

val <T> LiveData<T>.valueUpToDate: T?

Same as LiveData.getValue with the exception that the returned value is up to date even when the LiveData instance does not have an observer.

Functions

fun addSource(source: LiveData<out I>)

Adds a source, triggering a value update. Any future change to the added source's value will also trigger a value update.

fun removeSource(source: LiveData<out I>)

Removes a source, triggering a value update. Any future change to the added source's value will no longer trigger a value update.

fun setSources(newSources: List<LiveData<out I>>)

Replaces all sources, triggering a value update. Any future change to any of the new sources' values will also trigger a value update.

Inherited functions

fun <E> MutableLiveData<List<E>>.add(element: E): Boolean

Adds the specified element to the end of this MutableLiveData. The observers are notified of the new value.

fun <E> MutableLiveData<List<E>>.addAll(elements: Iterable<E>): Boolean

Adds all of the elements of the specified collection to the end of this MutableLiveData. The observers are notified of the new value if the list was changed.

fun <E> LiveData<out Collection<E>?>.any(predicate: (E) -> Boolean): Boolean

fun <T> MutableLiveData<T>.asLiveData(): LiveData<T>

Convenience method to create non-mutable LiveData fields without duplicating the type.

fun <T> LiveData<T>.check(predicate: (T) -> Boolean): Boolean

fun <E> MutableLiveData<List<E>>.clear()

Removes all elements from this MutableLiveData. The observers are notified of the new value if the list was changed.

@JvmName(name = "clearKV")

fun <K, V> MutableLiveData<Map<K, V>>.clear()

Removes all elements from a LiveData's Map, notifying observers of the new value.

fun <E> LiveData<out Collection<E>?>.contains(element: E): Boolean

operator fun <K> LiveData<out Map<K, *>>.contains(key: K): Boolean

Returns true if the LiveData's value contains the specified key.

fun <E> LiveData<out Collection<E>?>.containsAll(elements: Collection<E>): Boolean

fun <K> LiveData<out Map<K, *>>.containsKey(key: K): Boolean

Returns true if the LiveData's value contains the specified key.

fun <K, V> LiveData<out Map<K, V>>.containsValue(value: V): Boolean

Returns true if the LiveData's value maps one or more keys to the specified value.

fun <K, V> LiveData<out Map<K, V>>.find(predicate: (Map.Entry<K, V>) -> Boolean): Map.Entry<K, V>?

Finds the first entry from a LiveData's Map's value that matches the given predicate. Returns null if no entry is found or if the LiveData has no value.

fun <T, S> LiveData<out Collection<S>>.flatMap(mapFunction: (S) -> LiveData<out Collection<T>>): LiveData<Collection<T>>

Transforms a LiveData containing a list of type T, which contains all the child elements from each element in this LiveData list by flattening it.

flatMapBySource

fun <T, S> LiveData<out Collection<S>>.flatMapBySource(mapFunction: (S) -> LiveData<out Collection<T>>): LiveData<Collection<Pair<S, T>>>

Transforms a LiveData containing a list of type T, which contains all the child elements from each element in this LiveData list together with its source, by flattening it.

fun <E> LiveData<out Iterable<E>?>.forEach(operation: (E) -> Unit)

Performs operation on each entry in a LiveData's collection. Does nothing if the LiveData has no value.

fun <K, V> LiveData<out Map<K, V>>.forEach(operation: (Map.Entry<K, V>) -> Unit)

Performs operation on each entry in a LiveData's Map. Does nothing if the LiveData has no value.

operator fun <K, V> LiveData<out Map<K, V>>.get(key: K): V?

Returns the value corresponding to the given key in the LiveData's value, or null if such a key is not present in the map or the LiveData has no value.

fun <K, V> LiveData<out Map<K, V>>.getOrDefault(key: K, defaultValue: V): V

Returns the value corresponding to the given key in the LiveData's value, or defaultValue if such a key is not present in the map or the LiveData has no value.

fun <K, V> LiveData<out Map<K, V>>.getOrElse(key: K, defaultValue: () -> V): V

Returns the value for the given key in the LiveData's value, or the result of the defaultValue function if there was no entry for the given key or the LiveData has no value.

fun <K, V> MutableLiveData<Map<K, V>>.getOrPut(key: K, defaultValue: () -> V): V

Returns the value for the given key in the LiveData's value. If the key is not found, calls the defaultValue function, puts its result into the map under the given key and returns it. Creates a map if the LiveData has no value yet.

open fun getValue(): O?

hasActiveObservers

open fun hasActiveObservers(): Boolean

open fun hasObservers(): Boolean

fun <T, B : Boolean?> LiveData<B>.ifTrue(block: () -> LiveData<T>): LiveData<T?>

Executes and switchMaps to block if this has a true value. If this is false or null, it returns LiveData with value null. If this should not return null, ifTrueOrDefault can be used instead.

ifTrueOrDefault

fun <T : Any, B : Boolean?> LiveData<B>.ifTrueOrDefault(default: T, block: () -> LiveData<T>): LiveData<T>

Executes and switchMaps to block if this has a true value. If this is false or null, it returns LiveData with value default. This can be used instead of ifTrue when the default value should be something other than null. Note that this requires a non-null value for T in order for Kotlin's compiler to properly spot missing null-checks.

open fun isInitialized(): Boolean

mapToValueOrUnset

fun <K, V> LiveData<Map<K, V>>.mapToValueOrUnset(key: K): LiveData<V>

Maps the value of the provided key, if that key exists in this map. Otherwise, no value is set. This is useful in cases where the map may not contain the requested entry but the resulting LiveData is not nullable as the client does not care about a null value. This removes the need for the client to have null checks in its code wherever the resulting LiveData is used.

fun <T : Any, S : Any> LiveData<out Collection<S>>.merge(mapFunction: (S) -> LiveData<out T?>): LiveData<out Collection<T>>

Transforms LiveData containing a list that holds other LiveData instances into LiveData that contains the values from those LiveData instances. The returned LiveData will be updated when the source LiveData changes as well as when the internal LiveData instances change.

operator fun <E> MutableLiveData<List<E>>.minusAssign(element: E)

Removes a single instance of the specified element from a MutableLiveData, if it is present. The observers are notified of the new value if any of the specified elements was removed.

operator fun <E> MutableLiveData<List<E>>.minusAssign(elements: Iterable<E>)

Removes all elements from this MutableLiveData that are also contained in the given elements collection. The observers are notified of the new value if the list was changed.

operator fun <K, V> MutableLiveData<Map<K, V>>.minusAssign(key: K)

Removes the entry mapped by key from the LiveData's value, notifying observers of the new value.

fun <E> LiveData<out Collection<E>?>.none(predicate: (E) -> Boolean): Boolean

operator fun <T : Boolean?> LiveData<T>.not(): LiveData<T>

Negates the value of a boolean LiveData.

open fun observe(@NonNull p0: LifecycleOwner, @NonNull p1: Observer<in O>)

open fun observeForever(@NonNull p0: Observer<in O>)

inline fun <T : Any> LiveData<T>.observeNonNull(owner: LifecycleOwner, crossinline onChanged: (T) -> Unit): Observer<T>

Adds the given onChanged lambda as an observer within the lifespan of the given owner and returns a reference to observer. The events are dispatched on the main thread.

inline fun <T> LiveData<T>.observeOnce(lifecycleOwner: LifecycleOwner, crossinline onChanged: (T) -> Unit): Observer<T>

Observes this LiveData for one change only and returns the one-time observer. The returned observer can be used to stop observing the LiveData when a callback is no longer desired. It is safe to remove the observer while it is executing or has been executed already.

inline fun <T> LiveData<T>.observeWhile(lifecycleOwner: LifecycleOwner, crossinline onChanged: (T) -> Boolean): Observer<T>

Observes this LiveData as long as onChanged returns true and returns the observer. The returned observer can be used to stop observing the LiveData when a callback is no longer desired. It is safe to remove the observer while it is executing or after onChanged returns true.

operator fun <E> MutableLiveData<List<E>>.plusAssign(element: E)

Adds the specified element to the end of this MutableLiveData. The observers are notified of the new value.

operator fun <E> MutableLiveData<List<E>>.plusAssign(elements: Iterable<E>)

Adds all of the elements of the specified collection to the end of this MutableLiveData. The observers are notified of the new value if the list was changed.

operator fun <K, V> MutableLiveData<Map<K, V>>.plusAssign(map: Map<K, V>)

Appends all entries from the given map in a LiveData, notifying observers of the new value. Creates a map if the LiveData has no value yet.

open override fun postValue(p0: O)

fun <E> MutableLiveData<List<E>>.remove(element: E): Boolean

Removes a single instance of the specified element from a MutableLiveData, if it is present. The observers are notified of the new value if any of the specified elements was removed.

fun <E> MutableLiveData<List<E>>.removeAll(predicate: (E) -> Boolean): Boolean

Removes all elements from this MutableLiveData that match the given predicate. The observers are notified of the new value if the list was changed.

fun <E> MutableLiveData<List<E>>.removeAll(elements: Iterable<E>): Boolean

Removes all elements from this MutableLiveData that are also contained in the given elements collection. The observers are notified of the new value if the list was changed.

open fun removeObserver(@NonNull p0: Observer<in O>)

removeObservers

open fun removeObservers(@NonNull p0: LifecycleOwner)

fun <T : R?, R : Any> LiveData<T>.requireValue(): R

Gets the value stored in the LiveData object that should not be null.

operator fun <K, V> MutableLiveData<Map<K, V>>.set(key: K, valueToAdd: V)

Maps key to valueToAdd in LiveData's value. Creates a map if the LiveData has no value yet.

open override fun setValue(p0: O)

fun <T> LiveData<T>.withSetter(setter: (T) -> Unit): MutableLiveData<T>

Creates a MutableLiveData from LiveData by specifying the setter to use to the change the value.