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\t\t%s\t\t%s\t\t\t%s\t\t%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]\t\t[性别]\t\t[年龄]\t\t[身高]\t\t[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

//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)));

提取某一列(以name为例)

 //输出List
StudentInfo.printStudents(studentList);
//从对象列表中提取一列(以name为例)
List<String> nameList = studentList.stream().map(StudentInfo::getName).collect(Collectors.toList());
//提取后输出name
nameList.forEach(s-> System.out.println(s));

输出结果如下图:

Java8 使用 stream().map()提取List对象的某一列值及排重-LMLPHP

提取age列并排重(使用distinct()函数)

//提取前输出
StudentInfo.printStudents(studentList);
//从对象列表中提取age并排重
List<Integer> ageList = studentList.stream().map(StudentInfo::getAge).distinct().collect(Collectors.toList());
ageList.forEach(a-> System.out.println(a));

结果如下图:

Java8 使用 stream().map()提取List对象的某一列值及排重-LMLPHP

05-21 23:57
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