How to manage back button Activity in Android Kotlin

Question

I want to manage back button Activity with noHistory.

I add Two different Layout XML add With condition like this :

if(a == 0){attch onexml} if(a == 1){attch secondxml}  

when i reach secondxml from onexml , press back button its going to MainActivity , But i want to going onexml.and i used this type of code :

setSupportActionBar(cat_toolbar)
cat_toolbar.setNavigationIcon(R.drawable.ic_arrow_back_white_24dp)
cat_toolbar.setNavigationOnClickListener { 
startActivity(Intent(applicationContext, MainActivity::class.java))}

i attach two different activity_xml in single Activity using if condition . my App flow is

MainActivity -> (if(a == 0)onexml) 
                if(a == 1)secondxml). 

Start app with MainActicity then click on button goto WorkActivity but first view onexml . again click button of onexml going to secondxml. when i press backbutton of toolbar , it going to MainActivity but i want to goto first onexml and then press back for MainActivity.

Answer 1

   @Override
    public void onAttach(Activity activity) {
    cat_toolbar.setNavigationOnClickListener { 
    startActivity(Intent(applicationContext, MainActivity::class.java))}
    }