Chapter titles using titlesec

Question

I want my chapter titles to look like as asked in this post. I have followed the method suggested by "lockstep", that is, using package titlesec. It works perfectly fine but here is the question: I want this format for main chapters only and for the rest, that is Contents, Declaration, Index, Bibliography etc I want them centered with normal vertical spaces before and after the title. Pasting the code at the start of Chapter 1 solves the problem partially; it leaves the starting ones (contents, declaration) totally unchanged and applies the same format to Index and Bibliography. Please help.

Answer 1

Since the lists (ToC, LoF, LoT), the bibliography and index usually use \chapter* to format the heading in the document, you can simply use another \titleformat command for the numberless chapters:

\documentclass{book}

\usepackage{titlesec}
\titleformat{\chapter}[display]
  {\normalfont\bfseries\filcenter}{\LARGE\thechapter}{1ex}
  {\titlerule[2pt]\vspace{2ex}}[\vspace{1ex}{\titlerule[2pt]}]
\titleformat{name=\chapter,numberless}[display]
  {\normalfont\LARGE\bfseries\filcenter}{}{1ex}
  {\vspace{2ex}}[\vspace{1ex}]

\begin{document}

\tableofcontents
\chapter{The real numbers}

\end{document}

An image of the ToC

and another one, of a numbered chapter:

Answer 2

It appears that with the article class, the ToC title is made with \section* instead of \chapter*. In that case, the only change from Gonzalo's answer is to swap \section in for \chapter, and it has the expected effect.