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djun100
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Java中对象按照属性排序

 
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项目中经常需要用到比如地区列表按照中文的拼音首字母排序,但是有时候获取到的地区列表是对象的形式,有地区id,地区名称两个属性。这里主要涉及到两个技术点:

1、对象按属性排序;2、中文按拼音首字母排序。下面给出自己整理好的demo:

import java.text.Collator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.ComparatorUtils;
import org.apache.commons.collections.comparators.ComparableComparator;
import org.apache.commons.collections.comparators.ComparatorChain;

public class CompareTipA  {
    private int  id;
    private String  name;
    private String age;

    @SuppressWarnings("unchecked")
	public static void main(String []args) {
        ArrayList<Object> list = new ArrayList<Object>();
        list.add(new CompareTipA(1,"3","五"));
        list.add(new CompareTipA(2,"1","六"));
        list.add(new CompareTipA(5,"5","二"));
        list.add(new CompareTipA(3,"4","四"));
        list.add(new CompareTipA(8,"4","四"));
        list.add(new CompareTipA(4,"2","一"));

        Comparator mycmp = ComparableComparator.getInstance();
        mycmp = ComparatorUtils.nullLowComparator(mycmp);  //允许null   
        mycmp = ComparatorUtils.reversedComparator(mycmp); //逆序   
        
        ArrayList<Object> sortFields = new ArrayList<Object>();
		Comparator<Object> comparator=Collator.getInstance(java.util.Locale.CHINA);

        sortFields.add(new BeanComparator("name",comparator));  //name正序 (主)
        sortFields.add(new BeanComparator("id", mycmp));     //id逆序  (副)
        ComparatorChain multiSort = new ComparatorChain(sortFields);
        Collections.sort(list,multiSort);
        
        for (int i =0;i<list.size();i++) {
            System.out.println(list.get(i));    //输出
/*         [id=5,name=二,age=5]
			[id=2,name=六,age=1]
			[id=8,name=四,age=4]
			[id=3,name=四,age=4]
			[id=1,name=五,age=3]
			[id=4,name=一,age=2]*/
        }
    }

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

    public int getId() {
        return this.id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return this.name;
    }

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

//    public int compareTo(Object o) {
//        return this.comparator.compare(this, o);
//    }

    public String toString() {
        return "[id=" + this.id + ",name=" + this.name +",age=" + this.age +"]";
    }

    public String getAge() {
        return age;
    }

    public void setAge(String age) {
        this.age = age;
    }
} 
注意:需要导入的三个包:commons-beanutils-1.8.3.jar commons-collections-3.2.1.jar commons-logging-1.1.3.jar

commons-collections包不能用官网上的4.0版本,因为从源码中可以看见commons-beanutils包调用的就是commons-collections3.2版本的api,4.0的没兼容;commons-logging包也是commons-beanutils包所需要的。

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