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  • Java8 使用 stream().filter()过滤List对象(查找符合条件的对象集合)

     

     

    内容简介

    本文主要说明在Java8及以上版本中,使用stream().filter()来过滤一个List对象,查找符合条件的对象集合。

    List对象类(StudentInfo)

    public class StudentInfo implements Comparable<StudentInfo> {

    //名称
    private String name;

    //性别 true男 false女
    private Boolean gender;

    //年龄
    private Integer age;

    //身高
    private Double height;

    //出生日期
    private LocalDate birthday;

    public StudentInfo(String name, Boolean gender, Integer age, Double height, LocalDate birthday){
    this.name = name;
    this.gender = gender;
    this.age = age;
    this.height = height;
    this.birthday = birthday;
    }

    public String toString(){
    String info = String.format("%s %s %s %s %s",this.name,this.gender.toString(),this.age.toString(),this.height.toString(),birthday.toString());
    return info;
    }

    public static void printStudents(List<StudentInfo> studentInfos){
    System.out.println("[姓名] [性别] [年龄] [身高] [生日]");
    System.out.println("----------------------------------------------------------");
    studentInfos.forEach(s->System.out.println(s.toString()));
    System.out.println(" ");
    }

    @Override
    public int compareTo(StudentInfo ob) {
    return this.age.compareTo(ob.getAge());
    //return 1;
    }

    public String getName() {
    return name;
    }

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

    public Boolean getGender() {
    return gender;
    }

    public void setGender(Boolean gender) {
    this.gender = gender;
    }

    public Integer getAge() {
    return age;
    }

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

    public Double getHeight() {
    return height;
    }

    public void setHeight(Double height) {
    this.height = height;
    }

    public LocalDate getBirthday() {
    return birthday;
    }

    public void setBirthday(LocalDate birthday) {
    this.birthday = birthday;
    }
    }

    StudentInfo对象类

    测试数据

    复制代码
    //测试数据,请不要纠结数据的严谨性
    List<StudentInfo> studentList = new ArrayList<>();
    studentList.add(new StudentInfo("李小明",true,18,1.76,LocalDate.of(2001,3,23)));
    studentList.add(new StudentInfo("张小丽",false,18,1.61,LocalDate.of(2001,6,3)));
    studentList.add(new StudentInfo("王大朋",true,19,1.82,LocalDate.of(2000,3,11)));
    studentList.add(new StudentInfo("陈小跑",false,17,1.67,LocalDate.of(2002,10,18)));
    复制代码

    输出Students列表

     //输出List
    StudentInfo.printStudents(studentList);

    输出结果如下图:

     使用filter()过滤List

    //查找身高在1.8米及以上的男生
    List<StudentInfo> boys = studentList.stream().filter(s->s.getGender() && s.getHeight() >= 1.8).collect(Collectors.toList());
    //输出查找结果
    StudentInfo.printStudents(boys);

    结果如下图:

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  • 原文地址:https://www.cnblogs.com/shoshana-kong/p/14406687.html
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