The Job Role for AWS Java Developer is not confined to a set of task. They have multiple things to do. Few of the major task they do are as follows:-
- 
Code-level application security (IAM roles, credentials, encryption, etc.). 
- 
Developing and maintaining applications written for Amazon Simple Storage Service, Amazon DynamoDB, Amazon Simple Queue Service, Amazon Simple Notification Service, Amazon Simple Workflow Service, AWS Elastic Beanstalk, and AWS CloudFormation.  
- 
Developing with RESTful API interfaces. 
- 
Programming with AWS APIs. 
- 
General troubleshooting and debugging. 
Source: LinkedIn
I hope it helps!
Get your AWS Certification today and learn form the certified expert!
Thanks!