在Java8里创建Stream的几种方法

标签：

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;
import java.util.stream.Stream;

/**
 *
 * @author Kangjun Ways of Creating a Stream in Java 8
 */
public class StreamDemo {

    public static void main(String[] args) {

        arraysStream();

        collectionStream();

        generate();

        iterateStream();
        
        populaStream();
    }

    //From Arrays
    public static void arraysStream() {
        String[] arr = {"program", "creek", "program", "creek", "java", "web",
            "program"};
        Stream<String> stream = Stream.of(arr);
        System.out.println(Arrays.toString(arr));

    }

    //From Collections
    public static void collectionStream() {
        List<String> list = new ArrayList<>();
        list.add("Java");
        list.add("python");
        list.add("c++");
        list.add("c");
        list.add("lisp");

        Stream<String> stream = list.stream().filter(p -> p.length() > 3);
        String[] arr = stream.toArray(String[]::new);
        System.out.println(Arrays.toString(arr));
    }

    //Use Stream.generate()
    public static void generate() {
        Stream<String> stream = Stream.generate(() -> "test").limit(10);
        String[] strArr = stream.toArray(String[]::new);
        System.out.println(Arrays.toString(strArr));
    }

    //Use Stream.iterate()
    public static void iterateStream() {
        Stream<BigInteger> bigIntStream = Stream.iterate(BigInteger.ZERO, n -> n.add(BigInteger.TEN)).limit(10);
        BigInteger[] bigIntArr = bigIntStream.toArray(BigInteger[]::new);
        System.out.println(Arrays.toString(bigIntArr));
    }

    // From Popular APIs
    public static void populaStream() {
        String sentence = "Program creek is a Java site.";
        Stream<String> wordStream = Pattern.compile("\\W").splitAsStream(sentence);
        String[] wordArr = wordStream.toArray(String[]::new);
        System.out.println(Arrays.toString(wordArr));
    }
}

在Java8里创建Stream的几种方法

标签：

原文地址：http://my.oschina.net/jamaly/blog/387718