Question

I’m trying to run a java class that reads off some values from a JSON file. When I run it, however, I get the error:

java.io.FileNotFoundException: \file001.json (The system cannot find the file specified)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at java.io.FileReader.<init>(Unknown Source)
    at jsonPractice.main(jsonPractice.java:21)

The code I am using is:

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;

import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class jsonPractice {


        @SuppressWarnings("unchecked")
        public static void main(String[] args)
        {
            JSONParser parser = new JSONParser();
            try
            {
                Object obj = parser.parse(new FileReader("file001.json"));
                JSONObject jsonObject = (JSONObject) obj;
                String name = (String) jsonObject.get("name");
                System.out.println(name);

                long age = (Long) jsonObject.get("age");
                System.out.println(age);

                JSONArray msg = (JSONArray) jsonObject.get("messages");
                Iterator<String> iterator = msg.iterator();
                while (iterator.hasNext())
                {
                    System.out.println(iterator.next());
                }
            }
              catch (FileNotFoundException e) {
                e.printStackTrace();
            }
              catch (IOException e) {
                e.printStackTrace();
            }
              catch (ParseException e) {
                e.printStackTrace();
            }
        }
}

I’ve made sure to add the json jar to the build path and the file001.json is located inside the folder in the workspace for the project.

Thanks

Answer 1

You can get the current directory using –

String currentDir = new File(".").getAbsolutePath();

or

System.getProperty("user.dir");

Let’s consider your file is in /home/user/test/file/file001.json and you are getting /home/user/test/ using the current directory command(s). Then, append the rest file/file001.json like –

Object obj = parser.parse(new FileReader(currentDir + "file/file001.json"));