This book offers a comprehensive guide to implementing Zero-Trust security principles, cloud-based defenses, and robust application development practices. Through practical examples and expert advice, readers will gain the skills needed to design and develop secure Java applications that easily can tackle today's cyber threats. It builds focus on securing your source code through analysis, vulnerability detection, and automation. It also ensures the safety of your runtime environment for managing traffic and enables multi-factor authentication. While addressing data security concerns with encryption, anonymization, and cloud-based solutions, it also uses tools like OpenTelemetry for real-time threat detection. It manages sensitive information securely with Vault integration and explores passwordless authentication. Reference architectures, secure coding patterns, and automation practices are also provided to aid implementation.