How to download file from Url

fun downloadPdf(baseActivity:Context,url: String?,title: String?): Long {
        val direct = File(Environment.getExternalStorageDirectory().toString() + "/your_folder")

        if (!direct.exists()) {
            direct.mkdirs()
        }
        val extension = url?.substring(url.lastIndexOf("."))
        val downloadReference: Long
         var  dm: DownloadManager
         dm= baseActivity.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
        val uri = Uri.parse(url)
        val request = DownloadManager.Request(uri)
        request.setDestinationInExternalPublicDir(
                "/your_folder",
                "pdf" + System.currentTimeMillis() + extension
        )
        request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
        request.setTitle(title)
        Toast.makeText(baseActivity, "start Downloading..", Toast.LENGTH_SHORT).show()

        downloadReference = dm?.enqueue(request) ?: 0

        return downloadReference

    }

Bofore calling this method do check for Runtime permission:

Manifest.permission.WRITE_EXTERNAL_STORAGE

Using Async task

call when you want to download file : new DownloadFileFromURL().execute(file_url);

public class MainActivity extends Activity {

    // Progress Dialog
    private ProgressDialog pDialog;
    public static final int progress_bar_type = 0;

    // File url to download
    private static String file_url = "http://www.qwikisoft.com/demo/ashade/20001.kml";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        new DownloadFileFromURL().execute(file_url);

    }

    /**
     * Showing Dialog
     * */

    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case progress_bar_type: // we set this to 0
            pDialog = new ProgressDialog(this);
            pDialog.setMessage("Downloading file. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setMax(100);
            pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            pDialog.setCancelable(true);
            pDialog.show();
            return pDialog;
        default:
            return null;
        }
    }

    /**
     * Background Async Task to download file
     * */
    class DownloadFileFromURL extends AsyncTask<String, String, String> {

        /**
         * Before starting background thread Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }

        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection connection = url.openConnection();
                connection.connect();

                // this will be useful so that you can show a tipical 0-100%
                // progress bar
                int lenghtOfFile = connection.getContentLength();

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(),
                        8192);

                // Output stream
                OutputStream output = new FileOutputStream(Environment
                        .getExternalStorageDirectory().toString()
                        + "/2011.kml");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }

            return null;
        }

        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

        }

    }
}

if not working in 4.0 then add:

StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy); 

use below library:

  implementation 'com.mindorks.android:prdownloader:0.5.0'

code for downloading video from a given url is below:

 fun downfile(urll:String,fileName:String){



    if(!isFilePresent(fileName)) {
        var mFile2: File? = File(Environment.getExternalStorageDirectory(), "WallpapersBillionaire")
        System.out.println("File Foond " + mFile2!!.absolutePath)
        var mFile3: File? = File(Environment.getExternalStorageDirectory(), "WallpapersBillionaire")

        var downloadId = PRDownloader.download(urll, mFile2!!.absolutePath, fileName)
                .build()
                .setOnStartOrResumeListener(object : OnStartOrResumeListener {
                    override fun onStartOrResume() {
                        System.out.println("??????????????????? start")
                    }
                })
                .setOnPauseListener(object : OnPauseListener {
                    override fun onPause() {
                    }
                })
                .setOnCancelListener(object : OnCancelListener {
                    override fun onCancel() {
                    }
                })
                .setOnProgressListener(object : OnProgressListener {
                    override fun onProgress(progress: Progress) {
                        circlePeView.visibility = View.VISIBLE

                        var per = (progress.currentBytes.toFloat() / progress.totalBytes.toFloat()) * 100.00
                        //var perint = per*100
                        System.out.println("::??????????????????? Per : " + per + " ?? : " + progress.currentBytes + " ?? : " + progress.totalBytes)

                        circlePeView.setProgress(per.toInt())
                    }
                })
                .start(object : OnDownloadListener {
                    override fun onDownloadComplete() {

                        circlePeView.visibility = View.GONE
                        circlePeView.setProgress(0)
                        prefs = getSharedPreferences(PREFS_FILENAME, 0)

                        val editor = prefs!!.edit()
                        editor.putString(wall, "WallpapersBillionaire/" + fileName)
                        editor.apply()

                        try {
                            val myWallpaperManager = WallpaperManager.getInstance(applicationContext)
                            try {
                                myWallpaperManager.setResource(R.raw.wallp)
                            } catch (e: IOException) {
                                // TODO Auto-generated catch block
                                e.printStackTrace()
                            }

                            val intent = Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER)
                            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
                            intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
                                    ComponentName(this@AnimattedViewpagerActivity, VideoLiveWallpaperService::class.java))
                            startActivity(intent)
                        } catch (e: Exception) {
                            val intent = Intent()
                            intent.setAction(WallpaperManager.ACTION_LIVE_WALLPAPER_CHOOSER)
                            try {
                                startActivity(intent)
                            }catch (e2: java.lang.Exception){
                                Toast.makeText(applicationContext,"Please long click on your home screen. Select Video Live Wallpapers form thier. Thanks",Toast.LENGTH_LONG).show()
                            }

                        }
                        System.out.println("??????????????????? complete")
                    }

                    override fun onError(error: Error) {
                        System.out.println("??????????????????? error " + error)
                    }
                })
        System.out.println("??????????????????? called")
    }else{
        System.out.println("File Foond ")
        circlePeView.visibility = View.GONE
        circlePeView.setProgress(0)
        prefs = getSharedPreferences(PREFS_FILENAME, 0)

        val editor = prefs!!.edit()
        editor.putString(wall, "WallpapersBillionaire/" + fileName)
        editor.apply()

        try {
            val myWallpaperManager = WallpaperManager.getInstance(applicationContext)
            try {
                myWallpaperManager.setResource(R.raw.wallp)
            } catch (e: IOException) {
                // TODO Auto-generated catch block
                e.printStackTrace()
            }

            val intent = Intent(WallpaperManager.ACTION_CHANGE_LIVE_WALLPAPER)
            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
            intent.putExtra(WallpaperManager.EXTRA_LIVE_WALLPAPER_COMPONENT,
                    ComponentName(this@AnimattedViewpagerActivity, VideoLiveWallpaperService::class.java))
            startActivity(intent)
        } catch (e: Exception) {
            val intent = Intent()
            intent.setAction(WallpaperManager.ACTION_LIVE_WALLPAPER_CHOOSER)

            try {
                startActivity(intent)
            }catch (e2: java.lang.Exception){
                Toast.makeText(applicationContext,"Please long click on your home screen. Select Video Live Wallpapers form thier. Thanks",Toast.LENGTH_LONG).show()
            }

        }
        System.out.println("??????????????????? complete")
    }
}

You read data from remote stream when you call input.read(buffer). But viewModelScope launches code on the Main thread by default. To fix the exception you should explicitly specify that you perform the download on another (IO) thread.

fun downloadFile() = viewModelScope.launch(Dispatchers.IO) {
        val responseBody = apiService.getData().body()
        saveFile(responseBody)
}

So after 3 days of wanting to jump off a cliff. I found the answer. Of course it was a few minutes after asking the question here (first question ever so be kind.). The only Issue is you need a SSL cert for HTTPS on the server retrieving the file. My server is http but i can get a cert in there and fix that. to Test i threw up a github repository and linked to the raw text file. Here is my solution if this saves you 3 days pour one out for me.

Thread {
            try {
                val url = URL("https://raw.githubusercontent.com/USERNAME/NeedHTTPSdontWanaSSL/main/info.txt")
                val uc: HttpsURLConnection = url.openConnection() as HttpsURLConnection
                val br = BufferedReader(InputStreamReader(uc.getInputStream()))
                var line: String?
                val lin2 = StringBuilder()
                while (br.readLine().also { line = it } != null) {
                    lin2.append(line)
                }
                Log.d("The Text", "$lin2")
            } catch (e: IOException) {
                Log.d("texts", "onClick: " + e.getLocalizedMessage())
                e.printStackTrace()
            }
        }.start()

Credit: answered Aug 12, 2018 at 9:29 Aishik kirtaniya Android - How can I read a text file from a url?