json 拼装空list、object

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class FastJsonArrayTest {
	public static void main(String[] args) {
		JSONObject jo = new JSONObject();
		jo.put("name", null);
		jo.put("age", 123);
		jo.put("list", new JSONArray());
		jo.put("obj", new JSONObject());
		System.out.println(jo.toJSONString());
	}
}

打印结果：

{"age":123,"list":[],"obj":{}}