rxjava : collectInto、collect、all、any、將集合中元素以逗號連接並返回

參考：

RxJava 算術和聚合操作符

tbruyelle / RxPermissions

tbruyelle / RxPermissions : 無界面fragment

collectInto

    /**
     * 將集合中元素以逗號連接並返回
     *     public final <U> Single<U> collectInto(
     *                       final U initialValue,
     *                       BiConsumer<? super U, ? super T> collector
     *     )
     */
    private fun collectIntoName(list: MutableList<String>): String? {
        return Observable.fromIterable(list)
            .filter {
                it.isNotEmpty()
            }
            .collectInto(StringBuilder(), { stringBuilder, item ->
                if (stringBuilder.isEmpty()) {
                    stringBuilder.append(item)
                } else {
                    stringBuilder.append(", ").append(item)
                }
            })
            .blockingGet()
            .toString()
    }

collect

    /**
     * 將集合中元素以逗號連接並返回
     *     public final <U> Single<U> collect(
     *                    Callable<? extends U> initialValueSupplier,
     *                    BiConsumer<? super U, ? super T> collector
     *     )
     */
    private fun collectName(list: MutableList<String>): String? {
        return Observable.fromIterable(list)
            .filter {
                it.isNotEmpty()
            }
            .collect({ StringBuilder() }) { stringBuilder, item ->
                if (stringBuilder.isEmpty()) {
                    stringBuilder.append(item)
                } else {
                    stringBuilder.append(", ").append(item)
                }
            }
            .blockingGet()
            .toString()

    }

all

    /**
     * 集合中是否都非空
     *     public final Single<Boolean> all(Predicate<? super T> predicate) {
     */
    private fun hasNoEmptyItem(list: List<String>): Boolean? {
        return Observable.fromIterable(list)
            .all {
                it.isNotEmpty()
            }.blockingGet()
    }

 

any

    /**
     * 集合中是否包含空元素
     *     public final Single<Boolean> any(Predicate<? super T> predicate) {
     */
    private fun hasEmptyItem(list: List<String>): Boolean? {
        return Observable.fromIterable(list)
            .any {
                it.isEmpty()
            }
            .blockingGet()
    }

測試

private val lists1: MutableList<String> = mutableListOf(
    "1",
    "10",
    "18",
    "",
    "101",
    "51"
)

private val lists2: MutableList<String> = mutableListOf(
    "1",
    "10",
    "18",
    "101",
    "51"
)


println("1===========================" + collectIntoName(lists1))
println("1===========================" + collectName(lists1))
println("2===========================" + hasNoEmptyItem(lists1))
println("3===========================" + hasEmptyItem(lists1))
println("=========================================================")
println("1===========================" + collectIntoName(lists2))
println("1===========================" + collectName(lists2))
println("2===========================" + hasNoEmptyItem(lists2))
println("3===========================" + hasEmptyItem(lists2))
//1===========================1, 10, 18, 101, 51
//1===========================1, 10, 18, 101, 51
//2===========================false
//3===========================true
//=========================================================
//1===========================1, 10, 18, 101, 51
//1===========================1, 10, 18, 101, 51
//2===========================true
//3===========================false