String str1 = "If I forget my promise to ";
String penalty = "Eat breakfast every morning,";
String str2 = " then I ";
String promise = "lose my favorite toy";
String strb = "<u><b><font color='#081137'>"+ penalty +",</font></b></u>";
String strc = "<u><b><font color='#081137'>"+ promise + "</font></b></u>";
String strd = str1 +strb+ str2 + strc;
tv_notification.setText(Html.fromHtml(strd));
или используйте этот код:
SpannableStringBuilder builder = new SpannableStringBuilder();
SpannableString text1 = new SpannableString(str1);
text1.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.silver)), 0, str1.length() - 1, 0);
builder.append(text1);
SpannableString text2 = new SpannableString(penalty);
text2.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.midnight)), 0, penalty.length(), 0);
text2.setSpan(new UnderlineSpan(), 0, penalty.length(), 0);
builder.append(text2);
SpannableString text3 = new SpannableString(str2);
text3.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.silver)),0, str2.length(), 0);
builder.append(text3);
SpannableString text4 = new SpannableString(promise);
text4.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.midnight)), 0, promise.length(), 0);
text4.setSpan(new UnderlineSpan(),0, promise.length(), 0);
builder.append(text4);
tv_notification.setText(builder);