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

lihua2915

最新推荐文章于 2021-02-23 21:28:53 发布

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分类专栏： Apache common 文章标签： Apache

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本文介绍了一个使用Java进行集合排序的例子，展示了如何利用Apache Commons库中的工具类实现复杂对象的多级排序。首先定义了对象属性及构造方法，然后通过ComparatorChain设置排序规则，实现了根据对象的id逆序排序作为主要排序条件，当id相同时再按照name属性的自然顺序进行排序。

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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;
}
}