Code Reborn AI-Driven Legacy Systems Modernization from COBOL to Java

Legacy software systems, especially those built on COBOL, are both a marvel and a menace. As of 2023, these systems power 70% of financial institutions, handling $3 trillion in daily transactions--a figure drawn from a comprehensive industry report [1]. Globally, an estimated 200 billion lines of COBOL code remain in use, a testament to its durability since its inception in 1959, as noted in a 2024 IEEE analysis [2]. These systems underpin critical operations--think payroll processing, account management, and loan calculations in banks and insurance firms. Yet, their age is a liability: complexity averages 18 paths per module, well above the modern ideal of 10, while coupling averages 8 dependencies, fostering a 30% higher defect rate than languages like Java [3]. Maintenance consumes 60% of IT budgets, a burden intensified by a dwindling COBOL workforce--now just 5% of developers, per a 2025 Gartner estimate [4]. Modernization is not optional; it is a necessity, and this study proposes an AI-driven solution to transform COBOL into Java, with React illuminating the results.