How do you control if your dog keeps on barking in public places.

Muzzles work, but I don't particularly like the whole idea of them. Of course they should be used in extreme cases, like if the dog is extremely aggressive. Dogs will bark and that's something you have to accept. However, you can train them not to bark in public. Whenever they are quiet you reward them, be it with praise or with treats. If you keep doing this, over time they will begin to learn.