java集合中对象排序

概述：本示例实现对象按年龄升序 人气升序排序功能   姓名升序 降序排序功能

 

 package ch02; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; /** * @author YaoShiyou 实现对象排序 * */ public class Person { // 姓名 private String name; // 年龄 private int age; // 人气 private int hobby; public Person(String name) { this.name = name; } public Person(String name, int age) { this(name); this.age = age; } public Person(String name, int age, int hobby) { this(name, age); this.hobby = hobby; } 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; } public int getHobby() { return hobby; } public void setHobby(int hobby) { this.hobby = hobby; } public static void main(String[] args) { List<Person> list = new ArrayList<Person>(); list.add(new Person("g1", 18, 122)); list.add(new Person("g2", 17, 244)); list.add(new Person("g3", 45, 243)); list.add(new Person("g4", 9, 67)); list.add(new Person("g5", 98, 2)); System.out.println("排序前---"); for (Person person : list) { System.out.println(person.getName() + "/t" + person.getAge() + "/t" + person.getHobby()); } // Collections调用sort 方法 参数为 Collections.sort(list, new AgeComparatorAsc()); System.out.println("年龄排序后----"); for (Person person : list) { System.out.println(person.getName() + "/t" + person.getAge() + "/t" + person.getHobby()); } Collections.sort(list, new hobbyComparatorAsc()); System.out.println("人气排序后----"); for (Person person : list) { System.out.println(person.getName() + "/t" + person.getAge() + "/t" + person.getHobby()); } Collections.sort(list, new NameComparatorAsc()); System.out.println("姓名升序排序后----"); for (Person person : list) { System.out.println(person.getName() + "/t" + person.getAge() + "/t" + person.getHobby()); } Collections.sort(list, new NameComparatorDesc()); System.out.println("姓名降序排序后----"); for (Person person : list) { System.out.println(person.getName() + "/t" + person.getAge() + "/t" + person.getHobby()); } } } // 实现比较器接口 采用Age升序排列 class AgeComparatorAsc implements Comparator<Person> { public int compare(Person p1, Person p2) { if (p1.getAge() > p2.getAge()) { return 1; } else if (p1.getAge() == p2.getAge()) { return 0; } else { return -1; } } } class hobbyComparatorAsc implements Comparator<Person> { public int compare(Person o1, Person o2) { if (o1.getHobby() > o2.getHobby()) { return 1; } else if (o1.getHobby() == o2.getHobby()) { return 0; } else { return -1; } } } class NameComparatorAsc implements Comparator<Person> { public int compare(Person o1, Person o2) { return o1.getName().compareTo(o2.getName()); } } class NameComparatorDesc implements Comparator<Person> { public int compare(Person o1, Person o2) { return o2.getName().compareTo(o1.getName()); } }

//输出结果

排序前---
g1 18 122
g2 17 244
g3 45 243
g4 9 67
g5 98 2
年龄排序后----
g4 9 67
g2 17 244
g1 18 122
g3 45 243
g5 98 2
人气排序后----
g5 98 2
g4 9 67
g1 18 122
g3 45 243
g2 17 244
姓名升序排序后----
g1 18 122
g2 17 244
g3 45 243
g4 9 67
g5 98 2
姓名降序排序后----
g5 98 2
g4 9 67
g3 45 243
g2 17 244
g1 18 122