如何将此代码更改为kotlin以查看firebase数据库中的pdf

import android.net.Uri
import android.webkit.WebView
import android.webkit.WebViewClient
import com.google.firebase.database.*

fun loadPDFFromFirebase(databaseReference: DatabaseReference, pdfKey: String, webView: WebView) {
    databaseReference.child("pdfs").child(pdfKey).addListenerForSingleValueEvent(object : ValueEventListener {
        override fun onDataChange(dataSnapshot: DataSnapshot) {
            val pdfUrl = dataSnapshot.getValue(String::class.java)
            if (pdfUrl != null) {
                val pdfUri = Uri.parse(pdfUrl)
                webView.settings.javaScriptEnabled = true
                webView.webViewClient = WebViewClient()
                webView.loadUrl("https://docs.google.com/gview?embedded=true&url=$pdfUri")
            } else {
                // PDF URL not found in the database
            }
        }

        override fun onCancelled(databaseError: DatabaseError) {
            // Error occurred while retrieving PDF URL from the database
        }
    })
}

val databaseReference = FirebaseDatabase.getInstance().reference
val webView = findViewById<WebView>(R.id.webView)
val pdfKey = "your_pdf_key"
FirebasePDFViewer.loadPDFFromFirebase(databaseReference, pdfKey, webView)