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 <T>
 */

public class ListSortUtil<T> {
	/**
	 * @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<T> 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<Video> targetList = new ArrayList<Video>();
		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<Video> sortList = new ListSortUtil<Video>();
		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]