  We consider Einstein gravity minimally coupled to a scalar field with a given
potential in general dimensions. We obtain large classes of static hairy planar
black holes which are asymptotic to AdS space-times. In particular, for a
special case $\mu=(n-2)/2$, we obtain new classes of exact dynamical solutions
describing black holes formation. We find there are two classes of collapse
solutions. The first class solutions describe the evolution start from AdS
space-time with a naked singularity at the origin. The space-time is linearly
unstable and evolves into stationary black hole states even under small
perturbation. The second class solutions describe the space-time spontaneously
evolves from AdS vacua into stationary black hole states undergoing non-linear
instability. We also discuss the global properties of all these dynamical
solutions.
