Reflection math and collision detection problem

I am now making a space shooting game,but I still dont know how the meteor should change its direction after being hit by the space ship just like the picture below(the arrow is the direction that the object is move)it should be simular to a pool game.For the collision detection part i used Seperating axis thereom.And is there a way to check collision detection with concave shape?I am using java right now,so I cant use that put movieclips around a shape and check if they r hitting another shape method,and I don’t want the putting some convex shapes together to make a concave shape method,because when you have to make a complex concave should it will be really annoying -thanks

you might want to use a physics engine I think box2d is ported to java. it wont fix the concave shapes issue…\