linear algebra - a question how to compute the eigenvalues of a matrix

I have a question:
Suppose I have a $n\times n$ matrix:
$$
\begin{bmatrix}
1 & 1 &...& 1 \\
1 & 1 &...&1 \\
\vdots&\vdots &\ddots & \vdots&\\
1 & 1 & ...&1 \\

\end{bmatrix}
$$
,then is there a easy way to compute the eigenvalues of the matrix?

How can I compute this matrix eigenvalue?