java如何獲取流stream呢?

轉自:

http://www.java265.com/JavaJingYan/202207/16566384353851.html

下文筆者講述使用Java代碼生成stream流的方法分享，如下所示:

stream流簡介

Java.util.stream.Stream是Java 8新加入的介面
目前它的使用率非常之高，那麼如何獲取及生成一個流呢？下文筆者將一一道來，如下所示:
 
-Collection集合都可使用stream預設方法獲取流
default Stream stream()

-Stream介面的靜態方法of可以獲取數組對應的流
static Stream of(T···values)
參數是一個可變參數，那麼我們就可以傳遞一個數組

例

public class DemoGetStream {
    public static void main(String[] args) {
        //把集合轉換為Stream流
        List<String> list = new ArrayList<>();
        Stream<String> stream1 = list.stream();

        Set<String> set = new HashSet<>();
        Stream<String> stream2 = set.stream();

        Map<String,String> map = new HashMap<>();
        //獲取鍵,存儲到一個Set集合中
        Set<String> keySet = map.keySet();
        Stream<String> stream3 = keySet.stream();

        //獲取值,存儲到一個Collection集合中
        Collection<String> values = map.values();
        Stream<String> stream4 = values.stream();

        //獲取鍵值對(鍵與值的映射關係 entrySet)
        Set<Map.Entry<String, String>> entries = map.entrySet();
        Stream<Map.Entry<String, String>> stream5 = entries.stream();

        //把數組轉換為Stream流
        Stream<Integer> stream6 = Stream.of(1, 2, 3, 4, 5);
        //可變參數可以傳遞數組
        Integer[] arr = {1,2,3,4,5};
        Stream<Integer> stream7 = Stream.of(arr);
        String[] arr2 = {"a","bb","ccc"};
        Stream<String> stream8 = Stream.of(arr2);
    }
}