Develop Reference

Empty ArrayList after using Volley in Kotlin

I'm working on a simple app where I add elements in a ListView dynamically, for this I'm using Volley to read JSON and then add all the information inside a data class, as I saw in other questions Volley is asynchronous so when I try to get the size of my list it return 0 because it was executed before Volley.
I can't figure out how to wait for volley to finish before continuing with the code in Kotlin, this is the code where I get the data:
private fun getUsers() {
val url = ""
val requestQueue = Volley.newRequestQueue(this)
val request = JsonObjectRequest(Request.Method.GET, url, null, {
response ->try {
val jsonArray = response.getJSONArray("" + "data")
for (i in 0 until jsonArray.length()) {
val distr = jsonArray.getJSONObject(i)
val getUser = distr.getString("Utilizador").toString()
val getCargo = distr.getString("Cargo").toString()
val getEstado = distr.getString("Estado").toString().toInt()
listUtilizadores.add(Utilizadores(getUser, getCargo, getEstado))
}
} catch (e: JSONException) {
e.printStackTrace()
}
}, { error -> error.printStackTrace() })
requestQueue.add(request)
}
And how I call it inside onCreate()
getUsers()
Log.i("Testing", "Value: " + listUtilizadores.size)
Thank you

Can you try with JsonArrayRequest.
val request =JsonArrayRequest(
url,
Response.Listener { response ->
if (response != null) {
for (i in 0 until response.length()) {
try {
val distr = response.getJSONObject(i)
val getUser = distr.getString("Utilizador").toString()
val getCargo = distr.getString("Cargo").toString()
val getEstado = distr.getString("Estado").toString().toInt()
listUtilizadores.add(Utilizadores(getUser, getCargo, getEstado))
}
} catch (e: JSONException) {
e.printStackTrace()
}
}, { error -> error.printStackTrace() })
requestQueue.add(request)
}

Return response of android volley in workmanager

I've been trying to implement android volley with Workmanager for background data upload. No issues at all with implementation, but it's really hard to catch and return response result via Result.success to register.
override fun doWork(): Result {
var volley = VolleySingleTon.getInstance(mContext)
.syncLocationData(mContext, location, success = Function { collection ->
ERROR HERE************
**Need to return the return Result.success()**
**but i can't return the above**
}, failure = Function { collection ->
ERROR HERE************
**Need to return the return Result.failure()**
**but i can't return the above**
})
}
Volley request method class
fun syncLocationData(
context: Context,
location: List<VehicleLocation>, success: Function<RestCollection, Any>, failure: Function<RestCollection, Any>
) {
var jsonObject: JSONObject? = null
val jsonString = RestUtil.getGson().toJson(location)
try {
jsonObject = JSONObject(jsonString)
} catch (e: JSONException) {
e.printStackTrace()
}
addToRequestQueue(
JsonObjectRequest(
Request.Method.POST,
AppConstants.WEB_SERVER.toString + AppConstants.SYNC_LOC_DATA.toString, jsonObject,
SuccessHandler(context, null, success),
ErrorHandler(context, null, failure)
)
)
}
The handler used to gather the result from response
class SuccessHandler(
val context: Context,
private val progressBar: ProgressBar?,
private val successCallBack: Function<RestCollection, Any>
) : Response.Listener<JSONObject> {
override fun onResponse(json: JSONObject?) {
if (json != null) {
progressBar?.visibility = View.GONE
val response: ApplicationResponse =
RestUtil.getGson().fromJson(json.toString(), ApplicationResponse::class.java)
successCallBack.apply(response.collection)
}
}
}
Is there any workaround for this? Thanks!!

You can use a RequestFuture which is a Volley object. It helps you create a synchronous call in the Worker class
#NonNull
#Override
public Result doWork() {
RequestFuture<JSONObject> future = RequestFuture.newFuture();
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, "https://jsonplaceholder.typicode.com/todos/1", null, future, future);
VolleySingleton.getmInstance(getApplicationContext()).addToRequestQueue(request);
try {
JSONObject response = future.get(60, TimeUnit.SECONDS); // this will block
Log.d(TAG, response.toString());
return Result.success();
} catch (InterruptedException e) {
e.printStackTrace();
// exception handling
return Result.failure();
} catch (ExecutionException e) {
e.printStackTrace();
return Result.failure();
// exception handling
} catch (TimeoutException e) {
e.printStackTrace();
return Result.failure();
}
}

Response Initilaze in Kotlin

i try this with Kotlin Android.
But it does not work because Resonse needs to be initialized.
But how can I initialize response
override fun funk(): Response {
var response : Response
try {
response = proceed()
} catch (e: SomeError) {
....
}
return response
}

You need to make it nullable:
override fun funk(): Response? {
var response : Response? = null
try {
response = proceed()
} catch (e: SomeError) {
....
}
return response
}
You could also condense this method:
override fun funk() =
try {
proceed()
} catch (e: SomeError) {
null
}

how to Authenticate with Volley in android

i have a web service in this url : https://server_IP:9443/api/v1/ssids.json/
but it needs login in this page : https://server_IP:9443/login
when i make the request with the credentials in the headers , i got "Unexpected response code 401"
so how can i authenticate and get the json.
here is my code :
val request = object : StringRequest(Request.Method.GET, url, Response.Listener { response ->
if (response != null) {
Log.e("Your Array Response", response)
} else {
Log.e("Your Array Response", "Data Null")
}
}, Response.ErrorListener { error -> Log.e("error is ", "" + error) }) {
override fun getHeaders() : Map<String, String> {
val username ="admin"
val password = "admin"
val auth = "$username:$password"
var data = auth.toByteArray()
var base64 = Base64.encodeToString(data, Base64.NO_WRAP)
var headers = HashMap<String, String>()
headers.put("Authorization",base64)
headers.put("accept-language","EN")
headers.put("Content-type","application/json")
headers.put("Accept","application/json")
return headers
}
}
val queue = Volley.newRequestQueue(this)
queue.add(request)

Write in a database with Android

I am trying to write in a database with the library Volley using Kotlin and when I try nothing happened. I used Postman to see if there is a problem from the server and all is okay. According to me the problem comes from this part of my code:
val stringRequest = object : StringRequest(Request.Method.POST, "myURL",
Response.Listener<String> { response ->
try {
val obj = JSONObject(response)
Toast.makeText(applicationContext, obj.getString("message"), Toast.LENGTH_LONG).show()
} catch (e: JSONException) {
e.printStackTrace()
}
},
object : Response.ErrorListener {
override fun onErrorResponse(volleyError: VolleyError) {
Toast.makeText(applicationContext, volleyError.message, Toast.LENGTH_LONG).show()
}
}) {
#Throws(AuthFailureError::class)
override fun getParams(): Map<String, String> {
val params = HashMap<String, String>()
params.put("name", name)
params.put("genre", genre)
return params
}
}
VolleySingleton.instance?.addToRequestQueue(stringRequest)
Thank you a lot to try to solve my problem !!!