  We study $K^+$ and $\Lambda$ flow in heavy-ion collisions at beam energies of
about 2A GeV. We present our results in both the `traditional' (i.e., in terms
of the average transverse momentum in the reaction plane) as well as `modern'
(i.e., in terms of coefficients of the Fourier analysis of azimuthal
distributions) methods of flow analysis. We find significant differences
between the $K^+$ and the $\Lambda$ flow: while the $\Lambda$ flow is basically
similar to that of nucleons, the $K^+$ flow almost disappears. This difference
is attributed chiefly to their different mean field potentials in dense matter.
The comparisons with the experimental data, as well as theoretical results from
independent calculations, indicate clearly the pivotal roles of both $K^+$ and
$\Lambda$ medium effects. We emphasize that similar experimental data from
independent collaborations are essential for the eventual verification of these
medium effects.
