Lambda语法及例子

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package com.example.pk.lambada;

import org.assertj.core.util.Lists;

import java.util.*;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class Test{
    public void TestTo(){
        List<String> s1 = Arrays.asList("sss","DDDf","MDdss");
        List<String> s2 =s1.stream().map(str->{
            System.out.println(this.getClass().getName());
            return str.toLowerCase();
        }).collect(Collectors.toList());
        s2.forEach(System.out::println);
    }
}
public class LambadaTest {
    public static void main(String[] args) {
        String[] m = {"ZZZ","sDSs","PySd"};
        List<String> proName = Arrays.asList(m);
//        List<String> lowercaseNames1 = proName.stream().map(name-> name.toLowerCase()).collect(Collectors.toList());
//        List<String> lowercaseNames1 = proName.stream().map(String::toLowerCase).collect(Collectors.toList());
//        System.out.println(lowercaseNames1);
        Arrays.sort(m,Comparator.comparing(String::toLowerCase));

        Integer[] h = {1,5,6,4,88,5,46,4};
//        List<Integer> integerList = Arrays.asList(h);
        Arrays.sort(h);
        List<Integer> integerList = Arrays.asList(h);
        System.out.println(integerList);
        integerList.forEach(System.out::println);

        String waibu = "lambda :";
        List<String> proStrs = Arrays.asList("Ni","Hao","Lambda");
        List<String>execStrs = proStrs.stream().map(chuandi -> {
            Long zidingyi = System.currentTimeMillis();
            return waibu + chuandi + " -----:" + zidingyi;
        }).collect(Collectors.toList());
        execStrs.forEach(System.out::println);

        Test test = new Test();
        test.TestTo();

        List<Integer> integerList1 = Lists.newArrayList(1,null,5,45,null,8);
        integerList1.stream().filter(Objects::nonNull).count();

        //使用Stream静态方法创建Stream
        //<1>
        Stream<Integer> integerStream = Stream.of(1,5,6,8);
        //<2>
        Stream.generate(new Supplier<Double>() {
            public Double get(){
                return Math.random();
            }
        });
        Stream.generate(() -> Math.random());
        Stream.generate(Math::random);

        //转换Stream
        //distinct 去重  filter 过滤  map 对Stream中包含使用给定的转换函数进行转换操作
        integerList1.stream().limit(1);
        integerList1.stream().skip(4);

        List<Integer> nums = Lists.newArrayList(1,1,null,2,3,4,null,5,6,7,8,9,10);
//        List<Integer> numsWithoutNull = nums.stream().filter(num -> num != null).
//                collect(ArrayList::new,
//                        ArrayList::add,
//                        ArrayList::addAll);
        List<Integer> numsWithoutNull = nums.stream().filter(Objects::nonNull).collect(Collectors.toList());
        numsWithoutNull.forEach(System.out::println);

        //reduce  参数两个   1 上一次函数的返回值，2 stream中的元素
        long d = nums.stream().filter(Objects::nonNull).reduce(0,(sum,item)->sum+item);
        System.out.println(d);

        //count、allMatch、anyMatch、findFirst、noneMatch、max、min
        System.out.println(nums.stream().allMatch(Objects::nonNull));
        System.out.println(nums.stream().filter(Objects::nonNull).anyMatch(item -> item>6));




    }
}