{"id":1376,"date":"2016-01-02T08:55:43","date_gmt":"2016-01-02T13:55:43","guid":{"rendered":"http:\/\/codinggorilla.domemtech.com\/?p=1376"},"modified":"2016-01-02T08:55:43","modified_gmt":"2016-01-02T13:55:43","slug":"a-short-practical-review-of-foreign-function-calls-in-java-c-c","status":"publish","type":"post","link":"http:\/\/165.227.223.229\/index.php\/2016\/01\/02\/a-short-practical-review-of-foreign-function-calls-in-java-c-c\/","title":{"rendered":"A Short, Practical Review of Foreign Function Calls in Java, C#, C++"},"content":{"rendered":"

Android<\/a> is a popular platform for smartphones, with ten of thousands of applications developed for it every year. For coding an Android app, there are a number of programming languages, but Java is the most popular. However,\u00c2\u00a0Xamarin<\/a> provides tools for writing applications in C# if you prefer. If you use Xamarin, but sometimes want to use an open-source library written in Java, you still can. The state of currently used, practical\u00c2\u00a0Foreign Function Interfaces<\/a>\u00c2\u00a0(FFI) on most platforms is similar. Of course, the difficulty is in the details.<\/span><\/p>\n

Generally, there are two ways for code in one language to call another: use a native function to call the foreign function; or, use reflection<\/a> to call the foreign function. A\u00c2\u00a0bindings interface<\/a>\u00c2\u00a0offers native functions to the whole foreign API.<\/p>\n

Java Native Interface (JNI)<\/a> provides a native interface to call non-Java code from Java. It also provides an API for use in C++ to invoke Java code, structured like Java’s reflection API.<\/p>\n

There are a number of tutorials on how to use JNI, but they are somewhat out of date. This article brings it forward–if only to\u00c2\u00a0a small degree, with “how to” explanations.<\/p>\n

<\/p>\n

Java Native Interface on Windows<\/h1>\n

Java to C# Call Using JNI<\/h2>\n

JNI provides a native interface for C++ functions in Java. For Java to call C#, a C++\/CLI wrapper layer must be created containing calls to C# code.<\/p>\n

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  1. Create a Java file (e.g., Program.java<\/em>) with a class.<\/li>\n<\/ol>\n