Java8新特性-Stream流

来自java.util.Stream.Stream;包当中
其中方法非常简单。 因其方法后面跟着函数式接口，所以可以非常便捷的使用lambda表达式来进行操作。  
大大优化代码

import java.util.*;
import java.util.stream.Stream;
public class SocketLearning  {

    public static void main(String[] args)    {
        
//        stream();
//        stream2();
//        streamCount();
        
//        streamLimit();
//        streamSkip();
//        streamConcat();
        streamFilter();
    }
    public static void streamFilter()
    {
        // 此方法返回的是Stream
        Stream<String> stream = Stream.of("张三丰","周迅","李白","张无忌");
        
        Stream<String> stream2 = stream.filter((String name)->{
            return name.startsWith("张");
        });
        stream2.forEach(name->System.out.println(name));
    }
    public static void stream()
    {
         List<String> list = new ArrayList<>();  list.add("张无忌");
         list.add("周芷若");
         list.add("赵敏");
         list.add("张强");
         list.add("张三丰");
         
         list.stream()
                     .filter(name->name.startsWith("张"))
                     .filter(name->name.length()==3)
                     .forEach(name->System.out.println(name));
         Stream.of("1");
         
    }
    public static void stream2()
    {
        Stream<String> stream = Stream.of("1","2","3","4");
        // 使用map方法，把他转换成Integer
        Stream<Integer> stream2 = stream.map((String s)->{
            return Integer.parseInt(s);
        });
        
        stream2.forEach(i->System.out.println(i));
    }
    public static void streamCount()
    {
        ArrayList<Integer> list = new ArrayList<Integer>();
        list.add(1);
        list.add(2);
        list.add(3);
        list.add(4);
        list.add(5);
        list.add(6);
        
        Stream<Integer> stream = list.stream();
        long count = stream.count();
        System.out.println(count);
    }
    public static void streamLimit()
    {
        // 取用前几个  如limit(4)等。是一个延迟方法
        String[] arr = {"喜羊羊","美羊羊","灰太狼","红太狼"};
        Stream<String> stream = Stream.of(arr);
        
        Stream<String> stream2 = stream.limit(2);
        stream2.forEach(i->System.out.println(i));
    }
    public static void streamSkip()
    {
        String[] arr = {"喜羊羊","美羊羊","灰太狼","红太狼"};
        Stream<String> stream = Stream.of(arr);
        
        Stream<String> stream2 = stream.skip(2);
        stream2.forEach(i->System.out.println(i));
        
    }
    
    public static void streamConcat()
    {
        Stream<String> stream = Stream.of("1","2","3","4");
        String[] arr = {"喜羊羊","美羊羊","灰太狼","红太狼"};
        Stream<String> stream2 = Stream.of(arr);
        
        Stream<String> stream3 = Stream.concat(stream, stream2);
        
        stream3.forEach(i->System.out.println(i));
        
    }
}