rótulo \theequation dentro de matemática

Question

Código:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\begin{document}
    \begin{align*}
        J
        &= J_0 + 2 m r^2 
        & \label{eq:asdf}\refstepcounter{equation}(\theequation) 
        && \tilde{J} 
        &= J_0 + 2 m \tilde{r}^2 & \refstepcounter{equation}(\theequation)
    \end{align*}
    \eqref{eq:asdf}
\end{document}

Saída:

Quero fazer referência (1).

Answer 1

Amsmath define \let\label=\@gobble em alinhamento*.

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\begin{document}
\let\goodlabel=\label
    \begin{align*}
        J
        &= J_0 + 2 m r^2 
        & \refstepcounter{equation}\goodlabel{eq:asdf}(\theequation)
        && \tilde{J} 
        &= J_0 + 2 m \tilde{r}^2 & \refstepcounter{equation}(\theequation)
    \end{align*}
    \eqref{eq:asdf}
\end{document}