初学Collection

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;

class Person implements Comparable<Person> {
    String name;
    int id;

    public Person(String name, int id) {
        this.id = id;
        this.name = name;
    }

    @Override
    public int compareTo(Person p2) {
        return name.compareTo(p2.name);
    }

    public String toString() {
        return name + '\t' + id;
    }
}

public class AppOfList {
    public static void main(String[] args) {
        //////////// ArrayList
        List<Person> people = new ArrayList<>();
        /// 排序有兩種方法
        people.add(new Person("John", 3));
        people.add(new Person("Alice", 2));
        for (Person p : people) {
            System.out.println(p);
        }
        Collections.sort(people);
        for (Person p : people) {
            System.out.println(p);
        }
        Collections.sort(people, new Comparator<Person>() {

            @Override
            public int compare(Person p1, Person p2) {
                if (p1.name.length() > p2.name.length())
                    return 1;
                if (p1.name.length() < p2.name.length())
                    return -1;
                return 0;
            }

        });
        for (Person p : people) {
            System.out.println(p);
        }
        /// remove 刪除時，根據刪除元素的位置決定使用ArrayList還是LinkedList
        ///注意，最後一個元素的序號時size-1
        List<Integer> ints = new ArrayList<>();
        List<Integer> ints2 = new LinkedList<>();
        time(ints);
        time(ints2);
    }

    public static void time(List<Integer> list) {
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1E5; i++)
            list.add(i);
        for (int i = 1000; i > 0; i--)
            list.remove(i);
        long end = System.currentTimeMillis();
        System.out.println(end - start);
    }
}