java中List按照指定字段排序工具类

文章标题：java中List按照指定字段排序工具类.

文章地址: http://blog.csdn.net/5iasp/article/details/17717179

 

包括如下几个类

 

1. 实体类

 

package com.newyear.wish;

/**
 * 实体类
 *
 */
public class Video {

    public Video(int id, String title, int hits) {
        super();
        this.id = id;
        this.title = title;
        this.hits = hits;
    }

    private int id;
    private String title;
    private int hits;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public int getHits() {
        return hits;
    }
    public void setHits(int hits) {
        this.hits = hits;
    }

}

2. list排序工具类

 

package com.newyear.wish;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
 *  List按照指定字段排序工具类
 *
 * @param
 */

public class ListSortUtil {
    /**
     * @param targetList 目标排序List
     * @param sortField 排序字段(实体类属性名)
     * @param sortMode 排序方式（asc or  desc）
     */
    @SuppressWarnings({ "unchecked", "rawtypes" })
    public void sort(List targetList, final String sortField, final String sortMode) {

        Collections.sort(targetList, new Comparator() {
            public int compare(Object obj1, Object obj2) {
                int retVal = 0;
                try {
                    //首字母转大写
                    String newStr=sortField.substring(0, 1).toUpperCase()+sortField.replaceFirst("\\w","");
                    String methodStr="get"+newStr;

                    Method method1 = ((T)obj1).getClass().getMethod(methodStr, null);
                    Method method2 = ((T)obj2).getClass().getMethod(methodStr, null);
                    if (sortMode != null && "desc".equals(sortMode)) {
                        retVal = method2.invoke(((T) obj2), null).toString().compareTo(method1.invoke(((T) obj1), null).toString()); // 倒序
                    } else {
                        retVal = method1.invoke(((T) obj1), null).toString().compareTo(method2.invoke(((T) obj2), null).toString()); // 正序
                    }
                } catch (Exception e) {
                    throw new RuntimeException();
                }
                return retVal;
            }
        });
    }

}

3. 测试类

package com.newyear.wish;

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

public class ListSortUtilTest {

    /**
     * @param args
     */
    public static void main(String[] args) {


        List targetList = new ArrayList();
        targetList.add(new Video(1,"title1",31));
        targetList.add(new Video(2,"title2",12));
        targetList.add(new Video(3,"title3",53));
        System.out.println("排序前: " + targetList);

        ListSortUtil sortList = new ListSortUtil();
        sortList.sort(targetList, "hits", "asc");
        System.out.println("排序后：" +targetList);

    }

}

 

测试执行结果：

排序前: [com.newyear.wish.Video@c17164, com.newyear.wish.Video@1fb8ee3, com.newyear.wish.Video@61de33]
排序后：[com.newyear.wish.Video@1fb8ee3, com.newyear.wish.Video@c17164, com.newyear.wish.Video@61de33]