在Java8里创建Stream的几种方法详解编程语言

创建Stream的方法共有5种，分别为如下

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)); 
    } 
}