And here's an article pointing out something you probably already knew. From the Honolulu Star Bulletin:
Cats are inquisitive and enjoy exploring, but that doesn't mean they are only happy outdoors. Keeping cats inside is best. Domestic cats might find as much satisfaction prowling through your closet as they would anywhere outside.In an urban environment, cats allowed to roam outdoors face danger every day. Tangles with traffic; exposure to fleas, ticks, poison and disease; and the temptation to fight other animals all shorten their life expectancy. Outdoor cats also require more visits to the veterinarian and can cause problems in your neighborhood.
Most cats adapt easily to staying indoors, as the stress of dodging cars and the dog next door disappears. But some cats might need extra attention or training to make the transition.
If your cat has always been an outdoor cat, slowly reduce the amount of time spent outside. Your cat will adjust and in a few weeks should be converted completely to the great indoors.
Introduce the litter box: Start with litter box training immediately. Place the litter box in a quiet area and bring the cat to the area frequently. It usually doesn't take long for cats to grasp the concept, and then you can begin to keep it inside for longer periods.