They just changed the rule after Dwight Howard came into the NBA from high school that you need at least one year of college Basketball to advance to the NBA.
An NBA player can be drafted or signed right out of high school.
NBA player Casper Ware played for Long Beach State.
NBA player Chris Andersen played for Blinn College.
NBA player Jared Dudley played for Boston College.
NBA player Reggie Jackson played for Boston College.
NBA player Will Barton played for Memphis.
NBA player Will Bynum played for Georgia Tech.
NBA player Bradley Beal played for Florida.
NBA player Aaron Brooks played for Oregon.
NBA player Aaron Gordon played for Arizona.
NBA player Aaron Gray played for Pittsburgh.
NBA player Adonis Thomas played for Memphis.