  The focusing of electric current by a single \textit{p-n} junction in
graphene is predicted. We show that precise focusing can be achieved by
fine-tuning the densities of carriers on the n- and p-sides of the junction to
equal values, whereas the current distribution in junctions with different
densities resembles caustics in optics. This finding can be utilized in the
engineering of electronic lenses and focused beam-splitters using
gate-controlled \textit{n-p-n} junctions in graphene-based transistors.
