List 集合的一些常用操作

import java.util.ArrayList;
import java.util.List;

class Student {

    private String name;
    private Integer age;

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "Perosn [name=" + name + ", age=" + age + "]";
    }
}

public class Test {
    public static void main(String[] args) {

        List<Student> students = new ArrayList<>();
        students.add(new Student("abc", 12));
        students.add(new Student("bcd", 20));
        students.add(new Student("cde", 17));
        students.add(new Student("def", 25));
        students.add(new Student("efg", 15));
        
        for (Student stu : students) {
            System.out.println(stu);
        }
    }

}
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在集合尾部添加元素

Student student = new Student("123", 12);
int endOfList = students.size();
students.add(endOfList, student);

Student [name=abc, age=12]
Student [name=bcd, age=20]
Student [name=cde, age=17]
Student [name=def, age=25]
Student [name=efg, age=15]
Student [name=123, age=12]
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根据某个字段进行排序

students.sort((x, y) -> Integer.compare(x.getAge(), y.getAge()));

Student [name=abc, age=12]
Student [name=123, age=12]
Student [name=efg, age=15]
Student [name=cde, age=17]
Student [name=bcd, age=20]
Student [name=def, age=25]
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根据某个属性去重

import static java.util.stream.Collectors.collectingAndThen;
import static java.util.stream.Collectors.toCollection;
import static java.util.Comparator.comparingLong;

List<Student> list = students.stream().collect(
    collectingAndThen(
        toCollection(() -> new TreeSet<>(comparingLong(Student::getAge))), ArrayList::new)
);

Student [name=abc, age=12]
Student [name=efg, age=15]
Student [name=cde, age=17]
Student [name=bcd, age=20]
Student [name=def, age=25]
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