Let’s say you have a TextView called etx. You would then use the following code:
final SpannableStringBuilder sb = new SpannableStringBuilder("HELLOO");
final StyleSpan bss = new StyleSpan(android.graphics.Typeface.BOLD); // Span to make text bold
final StyleSpan iss = new StyleSpan(android.graphics.Typeface.ITALIC); //Span to make text italic
sb.setSpan(bss, 0, 4, Spannable.SPAN_INCLUSIVE_INCLUSIVE); // make first 4 characters Bold
sb.setSpan(iss, 4, 6, Spannable.SPAN_INCLUSIVE_INCLUSIVE); // make last 2 characters Italic
etx.setText(sb);