java8，让代码更优雅

逃离我推掉我的手 2022-03-25 21:26 245阅读 0赞

使用lambda表达式和方法引用改进了一下代码，看起来舒服多了

package com.itheima.base.test.lambda;
    
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.List;
    import java.util.function.Predicate;
    
    public class PredicateTest {
        public static void main(String[] args) {
            List<String> languages = Arrays.asList("Java","Python","C++","Php","Scala");
            System.out.println("language which start with \"J\" ：");
            //filter(languages, str -> str.toString().startsWith("J")).forEach(s -> System.out.println(s));
            /*
             * 下面一行代码相对上一行代码改进了两个点：
             * 1.Predicate使用了泛型，toString（）方法不再需要
             * 2.方法引用简化代码
             */
            filter(languages, str -> str.startsWith("J")).forEach(System.out::println);
            System.out.println("language which end with \"a\" : ");
            filter1(languages,str->str.endsWith("a")).forEach(System.out::println);
        }
        private static List<String> filter(List<String> names, Predicate<String> condition){
            List<String> filteredNames = new ArrayList<>();
            for (String name : names) {
                if(condition.test(name)){
                    filteredNames.add(name);
                }
            }
            return filteredNames;
        }
    
        private static List<String> filter1(List<String> names,Predicate<String> condition){
            List<String> filteredNames = new ArrayList<>();
           //names.stream().filter(name -> condition.test(name)).forEach(e->filteredNames.add(e));
           //names.stream().filter(condition::test).forEach(filteredNames::add);
           names.stream().filter(condition).forEach(filteredNames::add);
           return filteredNames;
        }
    }