BeanComparator实现ArrayList中的元素按多个属性复合排序

最新推荐文章于 2021-02-23 21:28:53 发布

原创最新推荐文章于 2021-02-23 21:28:53 发布 · 180 阅读

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本文提供了一个使用Java进行对象排序的实例，展示了如何利用Apache Commons库实现复杂排序逻辑，包括主副排序规则的设定。

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import java.util.Collections;    
import java.util.Comparator;    
import java.util.ArrayList;    
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) {    

        //在列表中加入若干CompareTipA对象
        ArrayList<Object> list = new ArrayList<Object>();    
        list.add(new CompareTipA(1,"3","五"));    
        list.add(new CompareTipA(1,"1","六"));    
        list.add(new CompareTipA(1,"5","二"));    
        list.add(new CompareTipA(1,"4","四"));    
        list.add(new CompareTipA(4,"2","一"));    

        //创建一个排序规则
        Comparator mycmp = ComparableComparator.getInstance();    
        mycmp = ComparatorUtils.nullLowComparator(mycmp);  //允许null       
        mycmp = ComparatorUtils.reversedComparator(mycmp); //逆序       

        //声明要排序的对象的属性，并指明所使用的排序规则，如果不指明，则用默认排序
        ArrayList<Object> sortFields = new ArrayList<Object>();    
        sortFields.add(new BeanComparator("id", mycmp)); //id逆序  (主)    
        sortFields.add(new BeanComparator("name"));      //name正序 (副) 

        //创建一个排序链
        ComparatorChain multiSort = new ComparatorChain(sortFields); 

        //开始真正的排序，按照先主，后副的规则
        Collections.sort(list,multiSort);    

        for (int i =0;i<list.size();i++) {    
            System.out.println(list.get(i));    //输出    
        }    
        /**
         * 输出结果如下:
         * [id=4,name=2,age=一]
         * [id=1,name=1,age=六]
         * [id=1,name=3,age=五]
         * [id=1,name=4,age=四]
         * [id=1,name=5,age=二]
         */
    }    

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

——怎么样，很爽吧？？？？