A Java Concurrency developer designs, implements, and manages concurrent systems in Java applications. They utilize Java's concurrency API to handle multiple threads and processes simultaneously, improving application performance. Their tasks include writing thread-safe code, managing synchronization, handling thread intercommunication, and solving concurrency issues like deadlocks, livelocks, or race conditions. They also optimize code for multi-processor systems and ensure efficient resource utilization. Their role is critical in developing high-speed, scalable, and real-time systems where tasks run in parallel, such as big data processing, gaming, and real-time transaction systems.