Stream流中map方法_stream流中的map方法

一、Stream流中map方法

1、代码举例

    public void test() throws ParseException {
        List<People> peopleList = new ArrayList<People>();
        People people1 = new People("张三", 18);
        People people2 = new People("王五", 19);
        peopleList.add(people1);
        peopleList.add(people2);

        Stream<String> peopleStream = peopleList.stream().map(
                //使用匿名接口Function重写抽象方法apply,参数一为传入类型，参数二为传出类型
                new Function<People, String>() {
                    @Override
                    public String apply(People people) {
                        people.setName("姓名：" + people.getName());
                        return people.getName();
                    }
                }
        );
        peopleStream.forEach(s -> System.out.println(s));
        System.out.println("========================================================");

        Stream<People> peopleStream2 = peopleList.stream().map(
                //lambda
                s->addAge(s)
        );
        peopleStream2.forEach(s -> System.out.println(s));
    }

    public People addAge(People people){
        people.setAge(people.getAge()+1);
        return people;
    }
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2、实体类

public class People {
    private String name;
    private int age;

    public People(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public People() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "People{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

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3、效果

二、其他

Stream中of方法传入可变参数
Stream中map元素类型转化方法

1、stream流获取某一个字段集合

List<String> names = personList.stream()
                            .map(person -> person.getName())
                            .collect(Collectors.toList());
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