Generally, not all the cities in Indonesia are safe for travelling especially if you are alone. It would be better to travel in groups while avoid going out at night if possible. Some locals tend to target foreigners although they might not be rowdy or violent. In most cases, they will only try to cheat you. Take note of all the emergency numbers like your consulate and embassy here. The police can be reached at 110, fire department at 113 and medical at 118 and 119.