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/**
* @program JavaBooks
* @description: 流的一些例子
* @author: mf
* @create: 2020/01/23 17:39
*/
package com.java8;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;
import java.util.stream.Stream;
public class streamDemo {
public static void main(String[] args) {
List<String> strings = Arrays.asList("ddd3", "bbb", "ccc", "www", "eee", "ddd2", "bbb");
System.out.println("过滤：");
// 过滤
strings
.stream()
.filter((s) -> s.startsWith("d"))
.forEach(System.out::println);
System.out.println("排序：");
// 排序
strings
.stream()
.sorted()
.filter((s) -> s.startsWith("d"))
.forEach(System.out::println);
System.out.println("映射：");
strings
.stream()
.map(String::toUpperCase)
.sorted()
.forEach(System.out::println);
// match
System.out.println("匹配：");
boolean anyStartsWithA =
strings
.stream()
.anyMatch((s) -> s.startsWith("d"));
System.out.println(anyStartsWithA);
boolean allStartsWithA =
strings
.stream()
.allMatch((s) -> s.startsWith("d"));
System.out.println(allStartsWithA);
boolean noneStartsWithA =
strings
.stream()
.noneMatch((s) -> s.startsWith("a"));
System.out.println(noneStartsWithA);
System.out.println("计数：");
long count =
strings
.stream()
.filter((s) -> s.startsWith("d"))
.count();
System.out.println(count);
//规约
System.out.println("规约");
Optional<String> reduce = strings
.stream()
.sorted()
.reduce((s1, s2) -> s1 + "#" + s2);
reduce.ifPresent(System.out::println);
// 去重
System.out.println("去重");
strings.stream().distinct().forEach(s -> System.out.println(s));
// 字符串拼接
String reduce1 = Stream.of("A", "B", "C").reduce("", String::concat);
System.out.println(reduce1);
// 求最小值
Double reduce2 = Stream.of(-1.5, 1.0, -3.0).reduce(Double.MAX_VALUE, Double::min);
System.out.println(reduce2);
// 求和
Integer reduce3 = Stream.of(1, 2, 3, 4).reduce(0, Integer::sum);
System.out.println(reduce3);
// 求和
Optional<Integer> reduce4 = Stream.of(1, 2, 3, 4).reduce(Integer::sum);
System.out.println(reduce4.get());
}
}