The way that a person will answer this question depends on their attitude towards the causes of the riots.
A liberal would argue that society needs to do more for the underprivileged people who riot out of frustration with society. They would agree with your suggestion about employment. They would also say that the government should provide better schools in poor neighborhoods. They might argue that the government should provide more recreational facilities and programs. Finally, they would argue that the government should do a better job of improving relations between the police and the poor communities.
Conservatives, on the other hand, would argue that society needs to be tougher on people who break the laws. They would argue for harsh punishments for the people who rioted. They would argue that the government needs to put more effort into policing poor areas to create a sense of law and order in those areas.
As you can see, people of different ideologies would have very different perspectives on how to prevent future riots like the recent London riots.