This article explores calling C libraries like fopen, fclose, and fgets from Java using the Foreign Function and Memory (FFM) API from java.lang.foreign package. The creation of the LibC class, setting up fopen, and other functions are detailed, highlighting the verbosity of Java code and the necessary steps to call foreign functions. The role of Arena in memory allocation and freeing is emphasized, ensuring the safe use of memory in Java for C functions. The main method for accessing fopen, fgets, and fclose functions is outlined, providing a Java-flavored way of reading a file in C. Comparisons to JNI for foreign function calls are discussed, noting the safety and complexity of the FFM API. The potential for using jextract for generating foreign function bindings from header files is mentioned as a less manual process. References and links for further exploration are provided.
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