在Java8里创建Stream的几种方法

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));
}
}