Install apk code

private void installApk() {
        try {
            String fileName = Environment.getExternalStorageDirectory() + "/File.apk";

            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(Uri.fromFile(new File(fileName)), "application/vnd.android.package-archive"); //vnd.android.package-archive  va de cajón!
            startActivity(intent);
        } catch (Exception e) {
            e.getStackTrace();
        }
    }