NCCJ Meaning (Native Code Compiler for Java)

June 24, 2024

A Native Code Compiler for Java translates Java bytecode directly into machine code, enabling Java applications to run with the performance benefits of native executables. This approach bypasses the need for a Java Virtual Machine (JVM) at runtime, resulting in faster startup times and enhanced runtime efficiency.

native code compiler for java

What Is a Native Code Compiler for Java?

A Native Code Compiler for Java is a tool that converts Java bytecode into machine-specific code, allowing Java applications to run as native executables on a particular platform. This compilation process eliminates the need for a Java Virtual Machine (JVM) during execution, leading to significant improvements in startup time and runtime performance.

By directly translating bytecode to machine code, the compiler enables the application to leverage the full computational power and specific features of the host architecture. This method is especially beneficial for performance-critical applications, such as those requiring real-time processing or operating in resource-constrained environments.

Native code compilation helps to enhance security by reducing the attack surface associated with the JVM. It also simplifies the deployment process by providing a single, optimized executable. Despite these advantages, the approach must balance maintaining Java's cross-platform capabilities and managing the complexities of native code generation and optimization.

How Does a Native Code Compiler Work?

A Native Code Compiler works through the following steps:

  1. Bytecode input. The Java source code is first compiled into Java bytecode using a standard Java compiler.
  2. Bytecode analysis. The native code compiler takes the bytecode as input and analyzes it for optimization opportunities.
  3. Code optimization. The compiler performs various optimizations on the bytecode to improve performance, such as inlining methods and eliminating redundant code.
  4. Machine code generation. The optimized bytecode is then translated into machine-specific code for the target platform.
  5. Linking. The generated machine code is linked with necessary runtime libraries and other dependencies to produce a standalone executable.
  6. Output. The final output is a native executable that can run directly on the target platform without the need for a JVM.

Why Is NCCJ Important?

A Native Code Compiler for Java (NCCJ) is important for several reasons:

  • Performance improvement. By converting Java bytecode directly into machine code, NCCJ eliminates the need for interpretation by the JVM, resulting in faster startup times and improved runtime performance.
  • Resource efficiency. Running Java applications as native executables reduces the overhead associated with the JVM, making it suitable for resource-constrained environments, such as embedded systems and mobile devices.
  • Enhanced security. Eliminating the JVM decreases the attack surface, reducing potential security vulnerabilities. Native executables can also be more tightly controlled and secured.
  • Simplified deployment. A single, optimized native executable simplifies the deployment process, as there is no need to ensure the presence and compatibility of a JVM on the target system.
  • Compatibility with native libraries. NCCJ allows easier integration with platform-specific libraries and APIs, enabling developers to take full advantage of the underlying hardware and operating system features.
  • Suitability for real-time applications. For applications requiring real-time performance, such as high-frequency trading systems or real-time simulations, NCCJ provides the necessary execution speed and reliability.

NCCJ Examples

Native Code Compilers for Java (NCCJ) are specialized tools that translate Java bytecode into machine-specific code, enhancing performance and efficiency. Here are a few notable examples.


GraalVM is a high-performance runtime that provides benefits through its ability to compile Java bytecode into native machine code ahead of time (AOT). This results in improved startup times and reduced memory footprint compared to traditional JVM execution. GraalVM supports multiple languages, making it a versatile choice for polyglot applications. Its native image feature allows developers to create standalone executables, facilitating easier deployment and better resource management.

Excelsior JET

Excelsior JET is a commercial Java SE implementation that compiles Java applications into optimized native executables. It focuses on delivering performance improvements, enhanced security, and simplified distribution. By eliminating the need for a JVM at runtime, Excelsior JET ensures that applications start faster and use system resources more efficiently. This makes it particularly suitable for desktop applications, embedded systems, and other performance-sensitive environments.


Avian is a lightweight Java Virtual Machine and native code compiler designed to be simple and efficient. It can compile Java bytecode to native code ahead of time or use a just-in-time (JIT) compiler. Avian is particularly useful for embedded systems and environments where a full-featured JVM is impractical.

GNU Compiler for Java (GCJ)

Part of the GNU Compiler Collection (GCC), GCJ was an early effort to bring native compilation to Java. While it is no longer actively maintained, GCJ provided a valuable proof of concept for compiling Java code directly to machine code. It allowed developers to produce native executables and libraries from Java source code or bytecode, offering performance benefits and integration with other GCC-supported languages. Despite its discontinuation, GCJ's contributions paved the way for more advanced native compilers like GraalVM.

Anastazija is an experienced content writer with knowledge and passion for cloud computing, information technology, and online security. At phoenixNAP, she focuses on answering burning questions about ensuring data robustness and security for all participants in the digital landscape.