How Can I Efficiently Parse JSON Data from a URL in Java?

Parsing JSON from a URL in Java

While reading and parsing JSON from a URL in Java may seem straightforward, seemingly verbose examples can lead to confusion. However, with the help of third-party libraries, the process can be significantly simplified.

JSON Parsing with org.json

Utilizing the Maven artifact org.json:json provides a more concise solution:

JsonReader.java

import org.json.JSONException;
import org.json.JSONObject;

import java.io.*;
import java.net.URL;
import java.nio.charset.Charset;

public class JsonReader {

    // Utility method to read a stream and return its contents as a string
    private static String readAll(Reader rd) throws IOException {
        StringBuilder sb = new StringBuilder();
        int cp;
        while ((cp = rd.read()) != -1) {
            sb.append((char) cp);
        }
        return sb.toString();
    }

    // Method to read a JSON response from a URL and return it as a JSONObject
    public static JSONObject readJsonFromUrl(String url) throws IOException, JSONException {
        InputStream is = new URL(url).openStream();
        try {
            BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
            String jsonText = readAll(rd);
            JSONObject json = new JSONObject(jsonText);
            return json;
        } finally {
            is.close();
        }
    }

    public static void main(String[] args) throws IOException, JSONException {
        // Example usage: reading from Facebook's Graph API
        JSONObject json = readJsonFromUrl("https://graph.facebook.com/19292868552");
        System.out.println(json.toString());
        System.out.println(json.get("id"));
    }
}

Example Usage

In the main method, you can see an example of retrieving data from Facebook's Graph API, printing both the full JSON response and extracting a specific value (the "id" property).

Conclusion

This improved solution provides a concise and efficient way to read and parse JSON data from a URL in Java, greatly simplifying the task.

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