Автор оригинала: mkyong.
В Java 8 вы можете использовать Массивы.поток
или Stream.of
для преобразования массива в поток.
1. Массивы объектов
Для массивов объектов оба Arrays.stream
и Stream.of
возвращает тот же результат.
package com.mkyong.java8; import java.util.Arrays; import java.util.stream.Stream; public class TestJava8 { public static void main(String[] args) { String[] array = {"a", "b", "c", "d", "e"}; //Arrays.stream Streamstream1 = Arrays.stream(array); stream1.forEach(x -> System.out.println(x)); //Stream.of Stream stream2 = Stream.of(array); stream2.forEach(x -> System.out.println(x)); } }
Выход
a b c d e a b c d e
Просмотрите исходный код JDK.
/** * Returns a sequential {@link Stream} with the specified array as its * source. * * @paramThe type of the array elements * @param array The array, assumed to be unmodified during use * @return a {@code Stream} for the array * @since 1.8 */ public static Stream stream(T[] array) { return stream(array, 0, array.length); }
/** * Returns a sequential ordered stream whose elements are the specified values. * * @paramthe type of stream elements * @param values the elements of the new stream * @return the new stream */ @SafeVarargs @SuppressWarnings("varargs") // Creating a stream from an array is safe public static Stream of(T... values) { return Arrays.stream(values); }
2. Примитивные Массивы
Для примитивного массива/|Массивы.поток и
Stream.of вернет другой вывод.
package com.mkyong.java8; import java.util.Arrays; import java.util.stream.IntStream; import java.util.stream.Stream; public class TestJava8 { public static void main(String[] args) { int[] intArray = {1, 2, 3, 4, 5}; // 1. Arrays.stream -> IntStream IntStream intStream1 = Arrays.stream(intArray); intStream1.forEach(x -> System.out.println(x)); // 2. Stream.of -> StreamStream temp = Stream.of(intArray); // Cant print Stream directly, convert / flat it to IntStream IntStream intStream2 = temp.flatMapToInt(x -> Arrays.stream(x)); intStream2.forEach(x -> System.out.println(x)); } }
Выход
1 2 3 4 5 1 2 3 4 5
Просмотрите исходный код JDK.
/** * Returns a sequential {@link IntStream} with the specified array as its * source. * * @param array the array, assumed to be unmodified during use * @return an {@code IntStream} for the array * @since 1.8 */ public static IntStream stream(int[] array) { return stream(array, 0, array.length); }
/** * Returns a sequential {@code Stream} containing a single element. * * @param t the single element * @paramthe type of stream elements * @return a singleton sequential stream */ public static Stream of(T t) { return StreamSupport.stream(new Streams.StreamBuilderImpl<>(t), false); }
P.S Протестировано с Oracle JDK 1.8.0_77
Рекомендации
Оригинал: “https://mkyong.com/java8/java-how-to-convert-array-to-stream/”