JSON array from JSON object is returning null

Question

I want to read JSON array

"connectTo":[   
    {
        "url": "wss://localhost/opt/siml"
    }   
],

from JSON string :

{

"cluster":{
    "enabled":"true",
    "clusterName":"cluster0",
    "simlURL":"wss://localhost:5443/opt/siml"
},

"simlFieldWatchUrl":"fieldwatchholder.jsp",

"persistFolder":"clusterconfig/concentratorBPersist",

"sslCrtFile":"clusterconfig/certDirB/siml.crt",
"sslKeyFile":"clusterconfig/certDirB/siml.key",

"SIMLID":"TestServerB",

"localWebProxyServer":"localhost",
"localWebProxyPort":8080,
"SIMLProxyPort":8400,
"SIMLWebPort":8300,

"turnOnExtraSIMLWebSocket":"false",

"autoPromoteNewConnectionsFromPurgatory":true,

"connectTo":[   
    {
        "url": "wss://localhost/opt/siml"
    }   
],

"tempLogins":[
    {
        "username":"root",
        "password":"root"
    }
]

}

My code to read url is:

JSONArray connectTo = (JSONArray) config.get("connectTo");
                System.out.println("Connect to : " + connectTo);
                for (Object o : connectTo) {
                    JSONObject connect = (JSONObject) o;
                    String url = (String) connect.get("url");
                    System.out.println(url);
                }

But System.out.println("Connect to : " + connectTo); this is returning Connect to : []

I read some old question but did not get satisfactory answer. Please Help. And thank you in advance :)

Is this string your whole json? Valid json must start with { or [. — Guts
– Guts, Commented Mar 9, 2018 at 13:30
This string is just part of json i want to read. Whole json is big file. — p05p
– p05p, Commented Mar 9, 2018 at 13:31
Post Json with the proper format then we can help you extract the content — nimi0112
– nimi0112, Commented Mar 9, 2018 at 13:32
Yes, I tried like JSONObject connectTo = (JSONObject) config.get("connectTo"); but throwing casting exception. — p05p
– p05p, Commented Mar 9, 2018 at 13:35

Kokogino · Accepted Answer · 2018-03-13 07:08:49Z

3

I just assume config is a JSONObject.

JSONArray connectTo = config.getJSONArray("connectTo");

config.get() returns an Object while config.getJSONArray() returns a JSONArray.

edited Mar 13, 2018 at 7:08

answered Mar 9, 2018 at 13:36

Kokogino

1,0861 gold badge7 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

9 Comments

p05p Over a year ago

but same i said above for config.getJSONArray, it is showing cannot resolve method getJSONArray

Kokogino Over a year ago

What is the output of System.out.println(config.toString());?

p05p Over a year ago

{"cluster":{"simlURL":"wss:\/\/localhost:8200\/opt\/siml","clusterName":"cluster0","enabled":"true"},"tempLogins":[{"password":"root","username":"root"}],"autoPromoteNewConnectionsFromPurgatory":true,"turnOnExtraSIMLWebSocket":"false","SIMLWebPort":8200,"persistFolder":"clusterconfig\/concentratorAPersist","localWebProxyServer":"localhost","SIMLProxyPort":8100,"_sslDirectory":"clusterconfig\/certD","connectTo":[],"sslCrtFile":"clusterconfig\/certDirA\/siml.crt","localWebProxyPort":8080,"sslKeyFile":"clusterconfig\/certDirA\/siml.key","simlFieldWatchUrl":"fieldwatchholder.jsp"}

p05p Over a year ago

I ma sorry its messy but it is Json string

Kokogino Over a year ago

It looks like your "connectTo" IS actually empty. So there's nothing wrong with the code. And this JSON is completely different from the one in the question.

|

nimi0112 · Accepted Answer · 2018-03-09 13:39:28Z

1

Try this:

JSONArray connectTo =config.getJSONArray("connectTo");

                    System.out.println("Connect to : " + connectTo);
                    for (int i=0;i<connectTo.length();i++) 
    {
                        JSONObject connect = connectTo.getJSONObject(i);
                        String url = connect.get("url");
                        System.out.println(url);
                    }

answered Mar 9, 2018 at 13:39

nimi0112

2,1431 gold badge20 silver badges33 bronze badges

5 Comments

p05p Over a year ago

for config.getJSONArray, it is showing cannot resolve method getJSONArray.

nimi0112 Over a year ago

Where have you defined your config variable?

p05p Over a year ago

JSONObject config = (JSONObject) new JSONParser().parse(new FileReader(file)); and file is path of json file.

nimi0112 Over a year ago

@p05p JSONObject config = new JSONObject(new JSONParser().parse(new FileReader(file));

p05p Over a year ago

still no luck :(

Ph0b0x · Accepted Answer · 2018-03-09 13:43:52Z

0

I got it working like this, not sure if this helps:

var json = {
  "connectTo": [{
    "url": "wss://localhost/opt/siml"
  }]
};

for (var o = 0; o < json.connectTo.length; o++) {
  console.log(json.connectTo[o].url);
}

answered Mar 9, 2018 at 13:43

Ph0b0x

6748 silver badges21 bronze badges

1 Comment

p05p Over a year ago

I am sorry but for this i have to modify my json string. ?

Collectives™ on Stack Overflow

JSON array from JSON object is returning null

3 Answers 3

9 Comments

5 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

9 Comments

5 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related