Cloud-native Java applications represent a paradigm shift in how enterprise software is designed, developed,deployed, and managed. By leveraging cloud computing principles such as elasticity, scalability, resilience, andautomation, cloud-native architectures enable Java applications to efficiently meet modern business andperformance demands. This approach emphasizes microservices-based architectures, containerization,orchestration platforms, and DevOps-driven continuous integration and continuous deployment (CI/CD)pipelines. While Java remains a dominant language in enterprise environments due to its maturity, portability, andextensive ecosystem, adapting traditional Java applications to cloud-native environments introduces severalarchitectural and operational challenges. These include managing distributed systems complexity, optimizingstartup time and memory consumption, ensuring fault tolerance, maintaining security across services, andachieving effective observability. This paper explores the core architectures underpinning cloud-native Javaapplications, examines key technical and organizational challenges encountered during adoption, and outlines bestpractices for designing resilient, scalable, and maintainable systems. Emphasis is placed on modern Javaframeworks, cloud-native design patterns, performance optimization techniques, and governance strategies thatcollectively enable organizations to fully realize the benefits of cloud-native Java development.