Leave Management System Java Developer

I require a Java developer to create a customized Leave Management System. The primary functionalities to be incorporated are as follows:

- Employee Self-Service Portal: Employees should be able to log in and request leave independently.
- Leave Request and Approval Workflow: The system should allow managers to review and approve or reject leave requests.
- Leave Balance Tracking: It should keep an updated record of each employee's remaining leave balance.

Please be aware that this must be a standalone system with no integration requirements with other systems.

In terms of user roles, the system should support employees, managers, and HR administrators each with distinct permissions and capabilities.

Ideal candidates will possess a good understanding of Java programming, a track record in system design and implementation, as well as prior experience developing similar HR tools. Proficiency in crafting secure, user-friendly portals and a deep understanding of workflow logic would be beneficial.