If you are going to stand in BRIGHT SUNLIGHT, and you have a choice between two outer garments, one black, the other white, but otherwise identical, then you will be warmer wearing the black one.
Black doesn't "attract" the sun's rays, it ABSORBS them (i.e., it converts the sunlight to heat.) White absorbs less, and reflects more. I don't know how much more exactly, but it's definitely enough to make a difference.
Of course, There's a lot of other factors besides just the color. What's going to keep you cooler in the burning desert? A black tee shirt and shorts? or a white parka and snow pants?
Also, the amount of the difference beetween black and white can depend on various facgtors. There'll be a huge difference between wearing a black leotard and a white leotard because the fabric which absorbs the heat is in close contact with your skin. On the other hand, the difference between a black or a white loose-fitting robe will not be nearly so much because air can circulate underneath and carry much of the heat away.
Umair,
The fact that black bodies are more efficient radiators than white bodies is not so relevant. We get rid of most of the heat of our bodies by evaporation (sweat), and by convection (air movement). Radiation plays a minimal role in getting rid of heat---we just aren't hot enough to radiate much energy. The surface of the sun, on the other hand is 5000 degrees, and *ALL* of the energy that we absorb from the sun, we absorb from its radiation. So, the color that we wear makes a big difference in how much heat we absorb, but only a tiny difference in how much we radiate back out.