A Core Java Developer designs, implements, and maintains Java applications. They participate in the entire software development life cycle, from concept and design to testing. They write efficient, testable, and reusable code, understanding Java's unique intricacies and translating them into functional software. They ensure designs comply with specifications and collaborate with cross-functional teams to define, design, and ship new features. They also troubleshoot and debug applications to optimize performance. Their role includes understanding client requirements and how they translate into application features, as well as continuously discovering, evaluating, and implementing new technologies to maximize development efficiency.