How to Easily Parse JSON from a URL in Java?

Simplest Way to Parse JSON from a URL in Java: A Concise Implementation

Reading and parsing JSON from a URL in Java can be straightforward with the help of external libraries. One such library is json, which provides a lightweight and user-friendly API for JSON handling.

Coding with JSON Library

Using the json Maven artifact, here's an example of a concise code snippet that achieves JSON parsing from a URL:

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

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.net.URL;
import java.nio.charset.Charset;

class JsonReader {

    // Utility method for reading all characters from a reader
    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();
    }

    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);
            return new JSONObject(jsonText);
        } finally {
            is.close();
        }
    }
}

Usage Example

In a main method, you can use this class to retrieve and parse JSON from a URL as follows:

public static void main(String[] args) throws IOException, JSONException {
    JSONObject json = JsonReader.readJsonFromUrl("https://graph.facebook.com/19292868552");
    System.out.println(json.toString());
    System.out.println(json.get("id"));
}

This code fetches JSON data from Facebook's Graph API, parses the response, and retrieves the specified fields.

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