What are the rights of a Property Owner?

Watching the move Pacific Heights, I first thought that all the property owners would have to do when the “ squatter” came onto their property was call the police and have him kicked off of their property. It is obviously not that easy. Apparently, “adverse possession, a law rooted in Anglo-Saxon history that has created a cottage industry of people who are attempting to capitalize on the weakness of others.”(PE.com)
“Almost every state allows adverse possession in some form. California law allows an individual to acquire title to a property if they've fenced it, openly occupied it without permission and paid property taxes continuously for five years.” Nevertheless, it seems the movie is a little dramatic, when the tenant first locked himself in the property owner should have broken down the door down because the tenant was not in right conduct. According to http://real-estate-law.freeadvice.com The length of time required for adverse possession in title varies - it could be as short as a few years or could run for twenty years or more. Typically public entities must establish a longer period of possession than individuals. Some states have adopted a rule which requires the adverse possessor to pay taxes each year on the land. The possession must be open for all to see. The possession must be exclusive to him or her (e.g., the fence in the above example, a driveway, road, etc.) The possession must be hostile to the actual owner of the land. To gain title to land through adverse possession requires strict compliance with the law, but can have dramatic impact upon land ownership rights.”