Android download manager completed

A broadcast is sent by the DownloadManager whenever a download completes, so you need to register a broadcast receiver with the appropriate intent action( ACTION_DOWNLOAD_COMPLETE ) to catch this broadcast:

To register receiver

registerReceiver(onComplete, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));

and a BroadcastReciever handler

BroadcastReceiver onComplete=new BroadcastReceiver() {
    public void onReceive(Context ctxt, Intent intent) {
        // your code
    }
};

You can also create AsyncTask to handle the downloading of big files

Create a download dialog of some sort to display downloading in notification area and than handle the opening of the file:

protected void openFile(String fileName) {
    Intent install = new Intent(Intent.ACTION_VIEW);
    install.setDataAndType(Uri.fromFile(new File(fileName)),"MIME-TYPE");
    startActivity(install);
}

you can also check the sample link

Sample Code