How to get a ProgressBar (or a button...) into class in android through koltin?

Issue

I need to know how to call a ProgressBar (or any other kind of button) into a class, outside of "onCreate" method. I saw in Java I can do it calling findViewById(), however it's been rid of in Kotlin. For example I was trying a thing like this:

 var myProgressBar = findViewById(R.id.myProgressBar) as ProgressBar

But it gives me the unresolved reference for the find view method.

Thanks in advance for help

______________UPDATE____________________

Here's my DownloadManager custom class

class DownloadSoundController(context: Context): Activity() {

val downloadManager = context.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
.....
.....
      Thread(Runnable{
        while (starter) {
            var query = DownloadManager.Query()
            query.setFilterById(refid)
            var c = downloadManager.query(query)

            if (c.moveToFirst()) {
                var totalSizeIndex = c.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES)
                var downloadedIndex = c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR)
                val fileSize = c.getLong(c.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES))
                var totalSize = c.getInt(totalSizeIndex)
                var downloaded = c.getInt(downloadedIndex)
                var progress = 0.0
                var raffronto: Long = -1

                if (fileSize != raffronto) {
                    progress = downloaded * 100.0 / totalSize
                    //println("myTag - downloaded % :$progress, downloaded var: $downloaded")
                    myProgressBar.progress = progress.toInt()
                    if (progress == 100.0) {
                        starter = false
                    }
                } else {
                    //println("myTag - downloaded = 100 progress: $progress, $downloaded")
                    myProgressBar.progress = progress.toInt()
                    if (progress == 100.0) {
                        starter = false
                    }
                }
            }
        }
    }).start()

Here's my manifest:

<application
        android:hardwareAccelerated="true"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

    <activity
            android:name="com.journeyapps.barcodescanner.CaptureActivity"
            android:screenOrientation="fullSensor"
            tools:replace="screenOrientation" />

    <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>

            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>
//ATTENTION
   <activity android:name="com.example.myapplication.DownloadSoundController"/> 
// here it returns ERROR, on default constructor

    <receiver android:name=".DownloadBroadcastManager">
        <intent-filter>
            <action android:name="android.intent.action.DOWNLOAD_COMPLETE"/>
        </intent-filter>
    </receiver>

</application>

_________UPDATE_2__________

I polished the code and I found several issues that sound really "weird" to me:

1) to stop the nullpoint exception about myProgressBar.progress = value, I found out I have to initialize myProgressBar.progress = 0

2) With println() my thread stamps into the log exactly, step by step, the downloaded amount of my file, but if I add the myProgressBar.progress = progress.toInt() (progress var is THE SAME I stamp into the println()!) in the Thread... it starts to be async in a way it EVEN STARTS BEFORE the download has begun.. leading to several errors and multiple downloads"

I really don't know what's going on

Solution

findViewById now returns a generic type which extends View (docs).

final <T extends View> T findViewById(...)

You can use

val progressBar = findViewById<ProgressBar>(R.id.myProgressBar)

Answered By - LppEdd