1、错误描述

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/collections/map/ListOrderedMap

at net.sf.json.JSONObject.(JSONObject.java:1450)

at net.sf.json.util.CycleDetectionStrategy.(CycleDetectionStrategy.java:37)

at net.sf.json.JsonConfig.(JsonConfig.java:65)

at net.sf.json.JSONArray.fromObject(JSONArray.java:105)

at com.you.model.ListToJSON.main(ListToJSON.java:29)

Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections.map.ListOrderedMap

at java.net.URLClassLoader$1.run(URLClassLoader.java:366)

at java.net.URLClassLoader$1.run(URLClassLoader.java:355)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:354)

at java.lang.ClassLoader.loadClass(ClassLoader.java:425)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)

at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

... 5 more

2、错误原因

/**

* 将List转换成JSON

*/

package com.you.model;

import java.util.ArrayList;

import java.util.List;

import net.sf.json.JSONArray;

/**

* @author YouHaiDong

*

*/

public class ListToJSON

{

/**

* @param args

*/

public static void main(String[] args)

{

List list = new ArrayList();

list.add("春天");

list.add("夏天");

list.add("秋天");

list.add("冬天");

JSONArray jsonArray = JSONArray.fromObject(list);

System.out.println("List转换成JSON：" + jsonArray.toString());

}

}

从“Caused by: java.lang.ClassNotFoundException: org.apache.commons.collections.map.ListOrderedMap”可以看出，缺少jar

3、解决办法

将“commons-collections-3.1.jar”复制到lib目录下