When working with JSON in Java, developers may encounter issues like java.lang.ClassNotFoundException: org.apache.commons.lang.exception.NestableRuntime, often due to missing dependencies. For example, the net.sf.json library requires several JAR files: commons-beanutils-1.9.1.jar, commons-collections-3.2.1.jar, commons-lang-2.6.jar, commons-logging-1.2.jar, and ezmorph-1.0.6.jar. Managing these dependencies can be cumbersome, and commons-lang has not been updated since 2011, making it less maintainable.

Modern alternatives like Google's Gson, Alibaba's FastJSON, and Jackson offer better maintenance and features. Jackson excels at JSON-object mapping but can be complex for simple use cases. FastJSON provides convenient static methods, while Gson is a balanced option. Given these factors, it's advisable to avoid net.sf.json and standardize on a single JSON library per project, such as FastJSON or Gson.

For converting a list of objects to a JSON array, FastJSON simplifies the process. Below is an example using FastJSON to generate a formatted JSON array from a list of maps:

package study.base.json.fastjson;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.serializer.SerializerFeature;

public class JsonExample {

    public static void main(String[] args) {
        List<map object="">> dataList = new ArrayList<>();
        for (int i = 0; i < 3; i++) {
            Map<string object=""> entry = new HashMap<>();
            entry.put("id", i);
            entry.put("age", 12);
            entry.put("username", "luzhifei");
            dataList.add(entry);
        }
        JSONArray jsonArray = JSONArray.parseArray(JSONArray.toJSONString(dataList));

        System.out.println(jsonArray.toString(SerializerFeature.PrettyFormat));
    }
}</string></map>

The output will be a formatted JSON array:

[
    {
        "username": "luzhifei",
        "id": 0,
        "age": 12
    },
    {
        "username": "luzhifei",
        "id": 1,
        "age": 12
    },
    {
        "username": "luzhifei",
        "id": 2,
        "age": 12
    }
]