With this open-jaw itinerary, you will need to also purchase a separate ticket from Bangkok to Jakarta. Those flights usually cost under $60 on a budget airlines. (Search Here).
Airport Code: BKK & CGK
Airline: All Nippon Airways (Airline Rating: 8/10)
Availability: January – March 2017
Nearby Airports? Yes, there are other options available out of SJC.
Outbound: 1 (NRT)
Inbound: 1 (HND)
Search Here (Google Flights)
Sample pricing (ana.com)