setTextAppearance deprecated android how to use?

Use TextViewCompat from support library:

TextViewCompat.setTextAppearance(tv, android.R.style.TextAppearance_Medium);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                titleTextView.setTextAppearance(R.style.TextAppearance_MaterialComponents_Headline6);
            } else {
                titleTextView.setTextAppearance(context, R.style.TextAppearance_MaterialComponents_Headline6);
            }

For API > 23, do :

tv.setTextAppearance(android.R.style.TextAppearance_Medium);