Java Community | Help. Code. Learn.•7mo ago

JSONArray

Hi guys, I am getting the following error when I am trying to run the code in the pastebin link and I dont really understand why as I copied from a doc which worked on the video....

Exception in thread "main" java.lang.ClassCastException: class org.json.simple.JSONObject cannot be cast to class org.json.simple.JSONArray (org.json.simple.JSONObject and org.json.simple.JSONArray are in unnamed module of loader 'app')
        at main.ConfigurationHandler.readConfigFile(ConfigurationHandler.java:32)
        at main.MainS.main(MainS.java:21)

Exception in thread "main" java.lang.ClassCastException: class org.json.simple.JSONObject cannot be cast to class org.json.simple.JSONArray (org.json.simple.JSONObject and org.json.simple.JSONArray are in unnamed module of loader 'app')
        at main.ConfigurationHandler.readConfigFile(ConfigurationHandler.java:32)
        at main.MainS.main(MainS.java:21)

https://pastebin.com/hGiZ1gz0 Halwp

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44 Replies

JavaBot•7mo ago

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nettyOP•7mo ago

Also, if anyone has a better idea to read out of a json file, let me know!

tjoener•7mo ago

ah well, it says you're trying to get an object when it's an array soooooooo what does the source look like?

nettyOP•7mo ago

Uh what source do you mean I sent a pastebin

szatkus•7mo ago

Apparently you have an object in your json file, but you have code that expects an array.

dan1st•7mo ago

Yeah this is a thing of json-simple If you have a {}, you need to cast to JSONObject, not JSONArray at that position Also it may be better to use json-java instead of json-simple json-simple is a bit questionable or you could use an object mapper

nettyOP•7mo ago

ok can you send an example

szatkus•7mo ago

Maybe read about JSON before tackling this project?

dan1st•7mo ago

of what exactly?

nettyOP•7mo ago

usage of json java or json java in general

dan1st•7mo ago

Can you show your JSON? btw in your code, the line JSONArray dbList = (JSONArray) obj; is likely the issue

szatkus•7mo ago

Wait, you learn from a video of someone who writes code like this?

    private void parseObj(JSONObject emp) {
        JSONObject empObj = (JSONObject) emp.get("database");
        //Get emp firstname
        SERVER_IP = (String) empObj.get("SERVER_IP");

    private void parseObj(JSONObject emp) {
        JSONObject empObj = (JSONObject) emp.get("database");
        //Get emp firstname
        SERVER_IP = (String) empObj.get("SERVER_IP");

dan1st•7mo ago

that's how json-simple works and why I wouldn't use it

tjoener•7mo ago

or Gson, I kinda like their object model

szatkus•7mo ago

Nah, it has getString. And nothing explains that double cast.

dan1st•7mo ago

it is json-simple, not json-java https://javadoc.io/doc/com.googlecode.json-simple/json-simple/latest/index.html

nettyOP•7mo ago

config.json

nettyOP•7mo ago

yup

Kyo-chan•7mo ago

So that's not an array. What do you mean, "it worked on the video"?

nettyOP•7mo ago

erm idk

szatkus•7mo ago

That looks... very crude.

Kyo-chan•7mo ago

You... Don't know what you meant? It's like when you add random words in a sentence, Que sera sera, you don't know what it means it's just for style?

nettyOP•7mo ago

Dude its obvious what I meant by the question I asked

Kyo-chan•7mo ago

What it obviously means is that you watched a video of a guy who lied and was saying that given some files, trying to run the entire project doesn't fail in the same way yours fail So unless you want to tell me that what it meant isn't the obvious...

nettyOP•7mo ago

What? My question was, how I can read values out of a json file I have never used that package before so how would I know its not working when you are using an array for an object

Kyo-chan•7mo ago

And my question was, what do you mean it worked on the video?

nettyOP•7mo ago

well he had the code in his main method and the config and it worked

szatkus•7mo ago

There's nothing that looks like an array in that JSON file.

nettyOP•7mo ago

I can tell that too

Kyo-chan•7mo ago

And you ensured you have the same code everywhere. So, fundamentally, you watched a video of a guy lying? Frustratingly enough I have not yet found a JSON library I like. I make mine for whenever I use JSON for personal purpose.

szatkus•7mo ago

I don't know, Gson is pretty good. Although I usually use Jackson for a sole reason that it's usually already in dependencies.

tjoener•7mo ago

yeah, I just wish gson was split That all the reflection based stuff was a separate library

nettyOP•7mo ago

I have checked and tried a few now but still could not find any good libary to do what I wanna do Might just stick with vertx

tjoener•7mo ago

vertx is slaying a mosquito with an elephant

dan1st•7mo ago

if you want one that works similar to json-simple (i.e you tell it what to access), you can use json-java:

JSONObject root = new JSONObject(yourJsonString);
String someElement = root.getString("abc");
JSONObject nestedObject = root.getJSONObject("def");

JSONObject root = new JSONObject(yourJsonString);
String someElement = root.getString("abc");
JSONObject nestedObject = root.getJSONObject("def");

if you want something that converts between JSON and your objects automatically, use gson or jackson

nettyOP•7mo ago

ok ill try

nettyOP•7mo ago

Ok so I managed to (kinda) do what I wanna do now with vertx, but now is my question... how do I access specific values or strings now, which are returned? Code I used:

package src;

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

import org.apache.commons.io.IOUtils;

import io.vertx.core.json.JsonObject;

public class Main {

    public static void main(String[] args) {
        try {
            
            String jsonStr = IOUtils.toString(new FileReader("config.json"));
            JsonObject jsonObj = new JsonObject(jsonStr);
            System.out.print(jsonObj.getString("database"));
            
        } catch(FileNotFoundException fnfe) {
            System.out.print("File not found");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
    
}

package src;

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

import org.apache.commons.io.IOUtils;

import io.vertx.core.json.JsonObject;

public class Main {

    public static void main(String[] args) {
        try {
            
            String jsonStr = IOUtils.toString(new FileReader("config.json"));
            JsonObject jsonObj = new JsonObject(jsonStr);
            System.out.print(jsonObj.getString("database"));
            
        } catch(FileNotFoundException fnfe) {
            System.out.print("File not found");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
    
}

szatkus•7mo ago

Lol, vert.x has its own JSON parser?

nettyOP•7mo ago

yu It works fire and vertx is a very good libary at all

szatkus•7mo ago

Anyway, something like jsonObj.getJsonObject("database").getString("SERVER_IP") should work.

nettyOP•7mo ago

ahhh omg i am dumb obv ill try tomorrow doe, thanks mate

dan1st•7mo ago

looks like a json-java wrapper or repackaging

tjoener•7mo ago

Using vertx is completely wrong for this, unless you're already using as a webserver

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