navigasi drawer item

MainActivity.java

 @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == R.id.nav_beranda) {
            viewPager.setCurrentItem(0);
        } else if (id == R.id.nav_info_akun) {
            Intent infoAkun = new Intent(MainActivity.this, InfoAkunActivity.class);
            startActivity(infoAkun);
        } else if (id == R.id.nav_riwayat_order) {
            Intent riwayatOrder = new Intent(MainActivity.this, RiwayatOrderActivity.class);
            startActivity(riwayatOrder);
        } else if (id == R.id.nav_kontak_kami) {
            try {
                Intent emailIntent = new Intent(Intent.ACTION_VIEW, Uri.parse("mailto:" + "kontak@masakini.xyz"));
                emailIntent.putExtra(Intent.EXTRA_SUBJECT, "Kontak MasakIni | ");
                startActivity(emailIntent);
            } catch (ActivityNotFoundException e) {
                //nothing
            }
        }
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;