I want to create a pick list of record types (account record types)  on a visual force page, and then which record type I choose that record type I want to show in that visual foce page. How do I do it please need the solution. Thank you.

I want to do Rest API integration with Java(AWS) and I am doing it first time. scenario is like we are sending some strings in map to AWS and then AWS will calculate and will return values in map. So I want to know how do I do it, I mean how to configure in my org and what code I need to write for REST API for call out?Tank you.

I have a custom field on Account called CountChild__c, so now I want to write a trigger on Account to count it's related contacts and update that fild  CountChild__c, so if a Account will have 3 Contacts then that CountChild__c field on Account should be update with the value 3. How can I achove it through trigger? Please guide me. Thank you.