Calling Fragment From Activity

I am trying to call a class whıch extends fragment from an activity class with startActivity() . It returns me cannot be cast to android.app.activity error. I am confused how can

Solution 1:

In the activity, you create an transaction to replace a fragment by another:

    FragmentSelectDate myFragment = new FragmentSelectDate();
    myFragment.setArguments(getIntent().getExtras());
    FragmentTransaction transaction = getSupportFragmentManager()
            .beginTransaction();
    transaction.replace(R.id.containerMain, myFragment,
                "FragmentSelectDate");
    transaction.addToBackStack(null);
    transaction.commit();