Why doesn't my text show up with style when using SpannableStringBuilder?

Use the spannable string builder for setting as text in textview :

contentView.setText(sb);

or else you can do like this :

SpannableStringBuilder spanstr = new SpannableStringBuilder("Bold please!");
spanstr.setSpan(new StyleSpan(Typeface.BOLD), 0, spanstr.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
spanstr.append("\n");
spanstr.append("The first line is bold. This one isn't.");
contentView.setText(spanstr);

use SpannableStringBuilder instance itself.

contentView.setText(sb);

output with your code:

Try the below. You need to set the spannable string to the textview. So set the spannable string to your text as below

String s= "The first line is bold. This one isn't";
String title="Bold Please!";  
TextView tv = (TextView) findViewById(R.id.some_id);
tv.setText("");
SpannableString ss1=  new SpannableString(title);
ss1.setSpan(new StyleSpan(Typeface.BOLD), 0, ss1.length(), 0);
tv.append(ss1);
tv.append("\n");
tv.append(s);

I tried the above and you can see the resulting snapshot below.