/**
     * check and delete the old package app if it exists.
     */
    private void checkOldPackage() {
        String packageName = "xxx.xxx.xxx.xxx";
        if (isAvilible(this, packageName)) {
            Intent uninstall_intent = new Intent();
            uninstall_intent.setAction(Intent.ACTION_DELETE);
            uninstall_intent.setData(Uri.parse("package:" + packageName));
            startActivity(uninstall_intent);
        }
    }

    private boolean isAvilible(Context cxt, String packagename) {
        PackageManager pm = cxt.getPackageManager();
        List<PackageInfo> pinfo = pm.getInstalledPackages(0);
        for (int i = 0; i < pinfo.size(); i++) {
            if (pinfo.get(i).packageName.equalsIgnoreCase(packagename)) {
                return true;
            }
        }
        return false;
    }