如何實現按照List集合中對象某個屬性排序？

工作中遇到按照類的某個屬性排列，這個屬性是個枚舉類型，按照要求的優先級排列。

可以使用ComparatorChain、BeanComparator、FixedOrderComparator實現。

舉一個例子：

學生類：包含姓名、年齡、性別、性格。性格是個枚舉類型。

性格類：枚舉類型，分為四類：內向，外向，太監，不知道四種類型。

SortUtil類：排序類。

Student.java

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

public class Student {

    private String name;
    private int age;
    private boolean sex;
    private Character character;

    public Student(String name, int age, boolean sex, Character character){
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.character = character;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }
    public int getAge() {
        return age;
    }

    public void setSex(boolean sex) {
        this.sex = sex;
    }
    public boolean getSex() {
        return sex;
    }

    public void setCharacter(Character character) {
        this.character = character;
    }
    public Character getCharacter() {
        return character;
    }

    @Override
    public String toString() {
        String sexString = sex == false ? "male" : "female";
        return "名字：" + name + " 年齡: " + age + " 性別: " + sexString + " 性格: " + character;
    }

    public static void main(String args[]) {
        Student student1 = new Student("spring", 20, false, Character.IN);
        Student student2 = new Student("summer", 18, false, Character.OUT );
        Student student3 = new Student("automn", 25, false, Character.UNKNOWN );
        Student student4 = new Student("winter", 25, true, Character.UNKNOWN);

        List<Student> list1 = new ArrayList<Student>();
        list1.add(student1);
        list1.add(student3);
        list1.add(student2);
        list1.add(student4);

        System.out.println("沒有排序之前：");
        for(Student student : list1) {
            System.out.println(student);
        }

        SortUtil.sortByWhat(list1);

        System.out.println("排序之后：");
        for(Student student : list1) {
            System.out.println(student);
        }


    }

}

 

Character類：

public enum Character {

    IN("內向"),
    OUT("外向"),
    BOTH("太監"),
    UNKNOWN("不知道");

    private String name;

    private Character(String name) {
        this.name = name;

    }

    public String getName() {
        return name;
    }

    public String toString() {
        return name;
    }

}

SortUtil類：

import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.comparators.ComparatorChain;
import org.apache.commons.collections.comparators.FixedOrderComparator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class SortUtil {

    private static final Log Logger = LogFactory.getLog(SortUtil.class);

    @SuppressWarnings("unchecked")
    public static void sortByWhat(List<Student> list){
        try{
            Character[] CharacterType = {Character.UNKNOWN,Character.IN ,Character.OUT,Character.BOTH};
            Comparator TypeComparator = new FixedOrderComparator(CharacterType);

            ComparatorChain moInfoComparator = new ComparatorChain();

            moInfoComparator.addComparator(new BeanComparator("character",TypeComparator));
            moInfoComparator.addComparator(new BeanComparator("age"),true);
            moInfoComparator.addComparator(new BeanComparator("name"));
            moInfoComparator.addComparator(new BeanComparator("sex"));

            Collections.sort(list, moInfoComparator);
        } catch (Exception e) {
            Logger.error(e.getMessage());
        }
    }

}

moInfoComparator.addComparator(new BeanComparator("character",TypeComparator));

這個類中首先按照性格屬性來排序，利用FixedOrderComparator設置優先級，性格屬性Character.UNKOWN排第一，

然后IN，其次OUT，最后BOTH。如果性格屬性相同，按照age排序，true表示逆序（默認排序是從小到大），然后按

照name，最后按照sex屬性排序。

需要導入commons-beanutils,commons-logging,commons-collections包。

結果：

可以看到排序之后首先按照性格排序，性格是枚舉類型，排序規則用FixedOrderComparator定義，性格相同按照年齡，所以：

<span style="white-space:pre">            </span>moInfoComparator.addComparator(new BeanComparator("character",TypeComparator));
            moInfoComparator.addComparator(new BeanComparator("age"),true);
            moInfoComparator.addComparator(new BeanComparator("name"));
            moInfoComparator.addComparator(new BeanComparator("sex"));

這四句話的順序決定了先已哪個屬性排序。