jdk8 lambda 常用流操作

/** *  */package com.lambdasTest.stream;import java.util.Arrays;import java.util.Comparator;import java.util.List;import java.util.function.BinaryOperator;import java.util.stream.Collectors;import java.util.stream.Stream;/** * jdk8 lambda 函数式编程之stream *  * @Date Oct 23, 2017 12:27:17 PM */public class StreamOfLambdas {    public static void main(String[] agrs) {        // collect(toList())        List<String> collected = Stream.of("a", "b", "c", "d").collect(Collectors.toList());        System.out.println(collected); // [a, b, c, d]        System.out.println(Arrays.asList("a", "b", "c", "d"));      //[a, b, c, d]        // map 将一个流中的值转换成一个新的流        collected = Stream.of("a", "b", "hEllo").map(string -> string.toUpperCase()).collect(Collectors.toList());        System.out.println(collected); // [A,B,HELLO]        // filter        List<String> beginningWithNumbers = Stream.of("a", "1abc", "5acs").filter(value -> isDigit(value.charAt(0))).collect(Collectors.toList());        System.out.println("filter: " + beginningWithNumbers); // [1abc, 5acs]        // flatmap 可用Stream替换值，然后将多个Stream连接成一个Stream        List<Integer> together = Stream.of(Arrays.asList(1, 2), Arrays.asList(3, 4)).flatMap(numbers -> numbers.stream()).collect(Collectors.toList());        System.out.println(together); // [1, 2, 3, 4]        // min and max        List<Track> tracks = Arrays.asList(new Track("bakai", 524), new Track("Vlolets for your furs", 373), new Track("Time was", 451));        Track shortestTrack = tracks.stream().min(Comparator.comparing(track->track.getLength())).get();        System.out.println(shortestTrack.getName().toString() + shortestTrack.getLength()); // Vlolets for your furs373        // reduce 从一组值中生成一个值        int count = Stream.of(1, 2, 3).reduce(0, (acc, element) -> acc + element);        System.out.println(count);      //6        BinaryOperator<Integer> accumulator = (acc, element) -> acc + element;        count = accumulator.apply(accumulator.apply(accumulator.apply(0, 1), 2), 3);        System.out.println(count);  //6    }    public static boolean isDigit(char c) {        return (int) c >= 48 && (int) c <= 57;    }}class Track {    private String name;    private int length;    /**     * @param name     *            曲目     * @param length     *            长度     */    public Track(final String name, final int length) {        super();        this.name = name;        this.length = length;    }    /**     * @return the name     */    public String getName() {        return name;    }    /**     * @param name     *            the name to set     */    public void setName(String name) {        this.name = name;    }    /**     * @return the length     */    public int getLength() {        return length;    }    /**     * @param length     *            the length to set     */    public void setLength(int length) {        this.length = length;    }}