  We study mean-field phases of the t-J model with long-range Coulomb
interaction. In the order of increasing doping density we find a classical
antiferromagnet, charge and spin stripes, and a uniform d-wave superconductor,
at the realistic doping parameters. Both in-phase and anti-phase stripes exist
as metastable configurations, but the in-phase stripes have a slightly lower
energy. The dependence of the stripe width and the inter-stripe spacing on the
doping is examined. Effects of fluctuations around the mean-field states are
discussed.
