Question About arrays

Yeah umm i got a question about arrays.
i made a new array called floor_a

floor_a = new Array();

then i assigned a object to a array

var f = new floor(); floor_a.push(f); addChild(f);

i tried to make it so when my player hits the floor it stops his gravity like in a smb game or sonic. So heres what i put in my player class

if (Main.floor_a.hitTestObject(x,y,true))			{


			}

i got this error apparently:
TypeError: Error #1006: hitTestObject is not a function. at Clip/active()

so how do i fix this?