JSON Parser Read Array

Question

Hello i am trying to parse a JSONFILE looking like this :

"ansible_facts": {
 "ansible_all_ipv4_addresses": [
 "xxx"
 ], 
 "ansible_all_ipv6_addresses": [], 
 "ansible_architecture": "xxx", 
 "ansible_bios_date": "xxx", 
 "ansible_bios_version": "xxx", 
 "ansible_cmdline": {
 "KEYBOARDTYPE": "xx", 
 "KEYTABLE": "xx", 
 "LANG": "xxx", 
 "SYSFONT": "xxx", 
 "crashkernel": "xxx", 
 "elevator": "xxx", 
 "nmi_watchdog": "1", 
 "quiet0": true, 
 "rd_LVM_LV": "xxx", 
 "rd_NO_DM": true, 
 "rd_NO_LUKS": true, 
 "rd_NO_MD": true, 
 "rhgb": true, 
 "ro": true, 
 "root": "xxx", 
 "selinux": "0"

...

Here is my Java program :

public static void main(String[] args) {
 JSONParser parser = new JSONParser();
 try {
 String filePath = "C:\\xxx\\xxx\\xxx\\JSON\\file";
 String file = readFileAsString(filePath);
 JSONObject jsonObject = (JSONObject)parser.parse(file);
 JSONArray ansibleFacts = (JSONArray)jsonObject.get("ansible_facts");
 for (Object o : ansibleFacts)
 {
 JSONObject fact = (JSONObject) o;
 String os = (String) fact.get("ansible_architecture");
 System.out.println(os);
 String name = (String) fact.get("ansible_processor_count");
 System.out.println(name);
 String pythonVersion = (String) fact.get("ansible_python_version");
 System.out.println(pythonVersion);
 }
 } catch (FileNotFoundException e) {
 e.printStackTrace();
 } catch (IOException e) {
 e.printStackTrace();
 } catch (ParseException e) {
 e.printStackTrace();
 }
}
private static String readFileAsString(String filePath) throws java.io.IOException{
 byte[] buffer = new byte[(int) new File(filePath).length()];
 BufferedInputStream f = null;
 try {
 f = new BufferedInputStream(new FileInputStream(filePath));
 f.read(buffer);
 } finally {
 if (f != null) try { f.close(); } catch (IOException ignored) { }
 }
 return new String(buffer);
}

I get the error : Exception in thread "main" java.lang.ClassCastException: org.json.simple.JSONObject cannot be cast to org.json.simple.JSONArray.

My JSON file starts directly with an ARRAY, i read several posts but can't understand why it doesn't work...

Answer 1

ansible_facts is not an array whereas ansible_all_ipv4_addresses or ansible_all_ipv6_addresses are arrays.

Some examples for accessing specific elements:

JSONObject ansibleFacts = jsonObject.getJSONObject("ansible_facts");
String architecture = ansibleFacts.getString("ansible_architecture");
JSONArray ipv4Addresses = ansibleFacts.getJSONArray("ansible_all_ipv4_addresses");
String xxx = ipv4Addresses.getString(0);

• user2823910: But then why is: String architecture = (String) jsonObject.get("ansible_architecture"); System.out.println(architecture); returning null ?
• user2823910: Thanks, but the problem is that i am using simple-jonson library and not the jonson-java library, so with yoru code i got => the method getJSONObject(String) is undefined for the type JSONObject
• Timuçin: Libraries can be different but the idea is straightforward. You should have understood how you could access arrays or regular elements.