protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    File fileBrochure = new File("/sdcard/fleetman.pdf");
    if (!fileBrochure.exists())
    {
         CopyAssetsbrochure();
    }

    /** PDF reader code */
    File file = new File("/sdcard/fleetman.pdf");

    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setDataAndType(Uri.fromFile(file),"application/pdf");
    intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    try
    {
        getApplicationContext().startActivity(intent);
    }
    catch (ActivityNotFoundException e)
    {
         Toast.makeText(MainActivity.this, "NO Pdf Viewer", Toast.LENGTH_SHORT).show();
    }
}

//method to write the PDFs file to sd card
    private void CopyAssetsbrochure() {
        AssetManager assetManager = getAssets();
        String[] files = null;
        try
        {
            files = assetManager.list("");
        }
        catch (IOException e)
        {
            Log.e("tag", e.getMessage());
        }
        for(int i=0; i<files.length; i++)
        {
            String fStr = files[i];
            if(fStr.equalsIgnoreCase("fleetman.pdf"))
            {
                InputStream in = null;
                OutputStream out = null;
                try
                {
                  in = assetManager.open(files[i]);
                  out = new FileOutputStream("/sdcard/" + files[i]);
                  copyFile(in, out);
                  in.close();
                  in = null;
                  out.flush();
                  out.close();
                  out = null;
                  break;
                }
                catch(Exception e)
                {
                    Log.e("tag", e.getMessage());
                }
            }
        }
    }