How to Convert JSON Array to ArrayList in Java

2025 年 3 月 31 日 | 阅读 3 分钟

在Java中，JSON在存储数据方面起着重要作用。ArrayList是一种大小可变的特殊数组。它也可以随时用于存储或删除数据。ArrayList使用List的所有方法，并保持插入顺序，因为它实现了List接口。在某些情况下，我们会以JSON格式获取数据，为了处理它，我们需要将其转换为类似数组的结构。ArrayList是访问数据的最佳方式，初学者通常会被问到如何将JSON数组转换为ArrayList。

服务器以JSON对象或JSON数组的形式返回响应，为了高效地处理它，我们需要将其转换为类似数组的结构，例如ArrayList。将JSON数组转换为ArrayList的过程相当简单。我们只需要遍历JSON数组，并将数组的每个元素添加到ArrayList中。

为了将JSON数组转换为ArrayList

我们将使用Maven，因为它就像添加依赖项一样简单。
我们将添加以下依赖项来使用JSONArray和JSONObject。

 <dependency>
    	<groupId>org.json</groupId>
    	<artifactId>json</artifactId>
    	<version>20180813</version>
</dependency>

我们将把JSON字符串转换为JSON对象。
我们将从JSON对象中获取JSON数组。
我们将创建一个空的Object类型的ArrayList。
之后，我们将遍历JSON数组，将它的每个元素推入ArrayList。

How to Convert JSON Array to ArrayList in Java

让我们看一个例子来理解如何将JSON数组转换为ArrayList。

我们有以下json字符串，从中读取JSON数据。

String json = "[{"name": "Java", "description": "Java is a class-based high-level programming language that follows the OOPs concepts."}, { "name": "Javascript", "description": "JavaScript is also a high-level, often just-in-time compiled, and multi-paradigm programming language." }, { "name": "Python", "description": "Python is another high-level, interpreted and general-purpose programming language." }]"

JSONArrayToArrayList.java

//Import packages and classes 
package JavaTpoint.JavaObjectToJSON;
import java.util.ArrayList;
import org.json.JSONArray;
import org.json.JSONObject;
//Creating JSONArrayToArrayList class
public class JSONArrayToArrayList {
	public static void main(String[] args){
		//Creating string of JSON data 
		String jsonData = "{\"languages\" : [{\"name\": \"Java\", \"description\":"
				+ " \" Java is a class-based high-level programming language that"
				+ " follows the OOPs concepts.\"},{\"name\": \"Javascript\","
				+ "\"description\": \"JavaScript is also a high-level, often "
				+ "just-in-time compiled, and multi-paradigm programming language."
				+ "\"},{\"name\": \"Python\",\"description\": \"Python is another "
				+ "high-level, interpreted and general-purpose programming language."
				+ "\"}]}";
		
		//Converting jsonData string into JSON object
		JSONObject jsnobject = new JSONObject(jsonData);
		//Printing JSON object
		System.out.println("JSON Object");
		System.out.println(jsnobject);
		//Getting languages JSON array from the JSON object
		JSONArray jsonArray = jsnobject.getJSONArray("languages");
		//Printing JSON array
		System.out.println("JSON Array");
		System.out.println(jsonArray);
		//Creating an empty ArrayList of type Object
		ArrayList<Object> listdata = new ArrayList<Object>();
		
		//Checking whether the JSON array has some value or not
		if (jsonArray != null) { 
			
			//Iterating JSON array
			for (int i=0;i<jsonArray.length();i++){ 
				
				//Adding each element of JSON array into ArrayList
				listdata.add(jsonArray.get(i));
			} 
		}
		//Iterating ArrayList to print each element

		System.out.println("Each element of ArrayList");
		for(int i=0; i<listdata.size(); i++) {
			//Printing each element of ArrayList
			System.out.println(listdata.get(i));
		}
	}
}

输出

JSON Object
{"languages":[{"name":"Java","description":"Java is a class-based high-level programming language that follows the OOPs concepts."},{"name":"Javascript","description":"JavaScript is also a high-level, often just-in-time compiled, and multi-paradigm programming language."},{"name":"Python","description":"Python is another high-level, interpreted and general-purpose programming language."}]}
JSON Array
[{"name":"Java","description":"Java is a class-based high-level programming language that follows the OOPs concepts."},{"name":"Javascript","description":"JavaScript is also a high-level, often just-in-time compiled, and multi-paradigm programming language."},{"name":"Python","description":"Python is another high-level, interpreted and general-purpose programming language."}]
Each element of ArrayList
{"name":"Java","description":"Java is a class-based high-level programming language that follows the OOPs concepts."}
{"name":"Javascript","description":"JavaScript is also a high-level, often just-in-time compiled, and multi-paradigm programming language."}
{"name":"Python","description":"Python is another high-level, interpreted and general-purpose programming language."}

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