Return to the activity main by clicking in a item of the navigation drawer

Question

Im working with an android app which have 3 fragments and the activity_main, all of them are listed in a navigation drawer. The question is how can i return to the activity main by clicking in a item of the navigation drawer.

The basic idea of waht I need is to close all the fragments open to return to the activity main

This is my code.

    if(id==R.id.taximetro){
    //this is my activity_main that i need to return   
        trans = true;
    } else if (id == R.id.factura) {
        fragment=new frmFactura();
        getSupportFragmentManager().beginTransaction().replace(R.id.content_main, fragment).addToBackStack(null).commit();
        trans = true;
    } else if (id == R.id.dispBlue) {
        fragment=new frmDispositivos();
        getSupportFragmentManager().beginTransaction().replace(R.id.content_main, fragment).addToBackStack(null).commit();
        trans = true;
    } else if (id == R.id.ayuda) {
        fragment=new frmAyuda();
        getSupportFragmentManager().beginTransaction().replace(R.id.content_main, fragment).addToBackStack(null).commit();
        trans = true;
    } 
    if (trans) {
        getSupportFragmentManager().beginTransaction().replace(R.id.content_main, fragment).commit();
        item.setCheckable(true);
        getSupportActionBar().setTitle(item.getTitle());
    }
    //getSupportFragmentManager().beginTransaction().replace(R.id.content_main, fragment).addToBackStack(null).commit();
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

Answer 1

Simple like you call fragments ..call your MainActivity

if you want check whats available on the view,

keep an ENUM value or other related way ..and change the value related the the view that you loaded ,and check a fragment is loaded or still the main view exists in your MainActivity using that ENUM value in your MainActivity call

so,

if a fragment view is loaded recall your MainActivity else just slide the navigation because you are already in the view of MainActivity without any fragment loaded on it

if(id==R.id.taximetro){
// call your activity again  if you want you can check that a fragment view is loaded  or not and do changes only when you need if there is a fragment view loaded.. or simply recall it 
 Intent intent = new Intent(this, MainActivity.class);
 startActivity(intent);
 finish();
    }