CODEWITHSUNDEEP
javac#json
Rodrigo Santos
Rodrigo Santos

Reputation: 99

JSON Simple unexpected character?

Unexpected character () at position 0.
    at org.json.simple.parser.Yylex.yylex(Yylex.java:610)
    at org.json.simple.parser.JSONParser.nextToken(JSONParser.java:269)
    at org.json.simple.parser.JSONParser.parse(JSONParser.java:118)
    at org.json.simple.parser.JSONParser.parse(JSONParser.java:81)
    at org.json.simple.parser.JSONParser.parse(JSONParser.java:75)
    at net.ddns.coolpvp.Testing.main(Testing.java:22)

I was making a TCP Server on Java, it was receiving a json and it gave this error, but I checked and the first character is '{', how can I fix this? I have no clue. I would be very grateful if you could help me
EDIT: The JSON is generated by .NET Framework in a C# Application and this is a JSON

{"Type":"level-info","LevelNumber":1}

This is how the C# Application is generating the JSON
Program.cs

using System;
using System.Text;
using System.Net.Sockets;
using System.IO;

namespace Testing
{
    public static class Program
    {
        public static void Main(string[] args)
        {
            TcpClient client = new TcpClient();
            client.Connect("localhost", 152);
            StreamWriter writer = new StreamWriter(client.GetStream(), Encoding.UTF8) { AutoFlush = true };
            writer.WriteLine(new RequestLevelInfo(1).ToJSONString());
            client.Close();
            Console.ReadKey(true);
        }
    }
}

RequestLevelInfo.cs

using System.Web.Script.Serialization;

namespace Testing
{
    public class RequestLevelInfo
    {
        public string Type { get { return "level-info"; } }
        public int LevelNumber { get; }
        public RequestLevelInfo(int level)
        {
            LevelNumber = level;
        }
        public string ToJSONString()
        {
            return new JavaScriptSerializer().Serialize(this);
        }
    }
}

The Server is reading it using a BufferedReader using the readLine method

package testing;

import java.net.Socket;
import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;

public class Testing {
    public static void main(String[] args) {
        try {
            ServerSocket server = new ServerSocket();
            server.bind(new InetSocketAddress(InetAddress.getByName("localhost"), 152));
            Socket client = server.accept();
            BufferedReader reader = new BufferedReader(new InputStreamReader(client.getInputStream(), "UTF-8"));
            String dataReceived = reader.readLine();
            JSONObject json = (JSONObject)new JSONParser().parse(dataReceived);
            System.out.println(json.toJSONString());
            client.close();
            server.close();
        } catch (IOException ex) {
            ex.printStackTrace(System.err);
        } catch (ParseException ex) {
            ex.printStackTrace(System.err);
        }
    }
}

Upvotes: 3

Views: 3949

Answers (2)

Joni
Joni

Reputation: 111389

The problem is in your C# code: it's sending incorrect JSON.

You are using the Encoding.UTF8 object. This object includes an invisible and unnecessary "byte order marker" character, which the Java JSON parser does not understand. JSON "must not" use a byte order mark character: JSON Specification and usage of BOM/charset-encoding

The solution is to create your own instance of UTF8Encoding. For example:

UTF8Encoding jsonEncoding = new UTF8Encoding(false);
StreamWriter writer = new StreamWriter(client.GetStream(), jsonEncoding) { AutoFlush = true };

Upvotes: 2

verity
verity

Reputation: 385

Hello, I thought about your code and changed something, here is my code:

public static void main(String[] args) {

    try {
        BufferedReader bufferedReader = java.nio.file.Files.newBufferedReader(Paths.get("test.json"));
        JSONObject data = (JSONObject) new JSONParser().parse(bufferedReader);
        System.out.println(data.get("Type"));
    } catch (Exception e) {
        e.printStackTrace();
    }

}

This is the content of the test.json File: {"Type":"level-info","LevelNumber":1}

My output is: level-info

Please check if you really have org.json.simple.JSONObject, org.json.simple.parser.JSONParser and org.json.simple.parser.ParseException imported. Not that you accidentally imported anything else.

Have fun, I hope I could help you!

EDIT

So, for me the error occurred with the following example:

public static void main(String[] args) {

    try {
        String string = "{name=Asel, number1=40.34, number2=29.343}";
        JSONObject object = (JSONObject) new JSONParser().parse(string);
        System.out.println(object.get("name"));
    } catch (Exception e) {
        e.printStackTrace();
    }

}

But not with this:

public static void main(String[] args) {

    try {
        String string = "{\"name\":\"Asel\", \"number1\":\"40.34\", \"number2\":\"29.343\"}";
        JSONObject object = (JSONObject) new JSONParser().parse(string);
        System.out.println(object.get("name"));
    } catch (Exception e) {
        e.printStackTrace();
    }

}

Therefore I wonder if your string that you really get from your TCP socket is exactly {"Type":"level-info","LevelNumber":"1"} and not something wrong liek this: {"Type"="level-info","LevelNumber"="1"}

To test it you could try to replace = with : in the string of TPC Socket and see if the error still occurs.

JSONObject json = (JSONObject)new JSONParser().parse(dataReceived.replace("=", ":"));

Upvotes: 1

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