JSONArray to usable Java/String array

Question

This is not a duplicate

My JSON is not in an JSONArray, My JSON is all objects. However I have passed the objects into an JSONArray as it was the only way I could figure out how to get each objects in 'patches'.

Right now I have everything converted to a JSONArray but I am unable to use it like I would like. The end goal of this is to take the JSON from the server end (Which is dynamic by the way, the patch files under patches get regenerated and new patches are added) Eventually I want to take that array list and use it to search for those packages in the users directory, but thats for later.

Right now I can't figure out how to convert data out of the JSONArray.

The JSON is currently structured as follows on the server end. (This structure CANNOT BE CHANGED).

{  
   "patches":{  
      "patch1.zip":{  
         "name":"patch1.zip",
         "type":"file",
         "path":"patch1.zip",
         "size":15445899,
         "checksum":"ed4e2275ba67470d472c228a78df9897"
      },
      "patch2.zip":{  
         "name":"patch2.zip",
         "type":"file",
         "path":"patch2.zip",
         "size":1802040,
         "checksum":"59de97037e5398c5f0938ce49a3fa200"
      },
      "patch3.zip":{  
         "name":"patch3.zip",
         "type":"file",
         "path":"patch3.zip",
         "size":6382378,
         "checksum":"25efa1e9145a4777deaf589c5b28d9ad"
      },
      "user.cfg":{  
         "name":"user.cfg",
         "type":"file",
         "path":"user.cfg",
         "size":819,
         "checksum":"489a315ac832513f4581ed903ba2886e"
      }
   }
}

I have looked into using GSON and JACKSON but can't figure out how to make them work when pulling out dynamic data from JSON.

I am using the org.json LIB.

ReadUrl.java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

public class ReadUrl {
    static String getUrl(String urlString) throws Exception {
        BufferedReader reader = null;
        try {
            URL url = new URL(urlString);
            reader = new BufferedReader(new InputStreamReader(url.openStream()));
            StringBuilder buffer = new StringBuilder();
            int read;
            char[] chars = new char[1024];
            while ((read = reader.read(chars)) != -1)
                buffer.append(chars, 0, read);
            return buffer.toString();
        } finally {
            if (reader != null)
                reader.close();
        }
    }
}

Main.java

import org.json.JSONArray;
import org.json.JSONObject;

public class Main {
    private static final boolean isDebugMode = true;
    /**
     * @param args the command line arguments
     * @throws java.lang.Exception
     */
    public static void main(String[] args) throws Exception  {
        String sReadURL = ReadUrl.getUrl("http://www.aerosimulations.com/wp-content/uploads/example.json");

        if (isDebugMode) {
            System.out.println(sReadURL);
        }

        JSONObject responseJSON = new JSONObject(sReadURL);
        JSONObject obj1_JSON = responseJSON.getJSONObject("patches");

        JSONArray jPatches = obj1_JSON.names();

        if (isDebugMode) {
            System.out.println(jPatches);
        }

        for(int i = 0; i < jPatches.length(); i++){

        }

    }
}

My requirement is, I need to be able to get the patch names from 'patches' and return a usable java array.

Possible duplicate of [Convert JSONArray to String Array](https://stackoverflow.com/questions/15871309/convert-jsonarray-to-string-array) — vinS, Dec 14 '17 at 04:14
Not duplicated, I did extensive research on how to do this before asking the question. Our JSON is setup in two different structures and I am not able to use getString. @vinS — MeltedPixel Mike, Dec 14 '17 at 04:17

score 1 · Accepted Answer · answered Dec 14 '17 at 04:48

I would use Jackson Tree Model for this case:

    //first, you create a mapper object
    ObjectMapper mapper = new ObjectMapper();

    //then you create a JsonNode instance representing your JSON root structure
    JsonNode root = null;
    try {
        root = mapper.readTree(json);
    } catch (IOException e) {
        e.printStackTrace();
    }

    //here you get the list of your patches nodes
    JsonNode list = root.path("patches");

    //then you can iterate through them and get any inner value
    for (JsonNode patch : list) {
        //for example, you can get a file name
        System.out.println(patch.path("name"));
    }

The output of this code will be:

patch1.zip
patch2.zip
patch3.zip
user.cfg

You literately solved two problems in one. I now understand how I can use jacksons (which from my understanding is a much better method). I can't thank you enough. Now I can use that to actually one by one do what I need with each patch files. That's pretty awesome. I could probably also make a string array and add each read line to those arrays. This will be perfect. Thanks for your help! — MeltedPixel Mike, Dec 14 '17 at 05:36

JSONArray to usable Java/String array

1 Answers1