Java runtime environment for FGL

Software requirements when using the Java Interface

Important: This topic is about JDK requirements for the FGL runtime system, to compile and execute server applications. To build GMA mobile applications, a different Java version may be required by Android™ tools. For more details, see Install Genero Mobile for Android.

In order to use the Java Interface in your application programs, you need the Java software installed and properly configured.

  • Install a Java Development Kit on development sites (if you need to compile your own Java classes)
  • Install a Java Runtime Environment on production sites (on the server where your programs are running)
Note: Over time, the Java platform has used different versioning systems, to distinguish a "Java developer version", from a "Java product version". For example, the Java developer version (JDK) 1.8 corresponds to the Java product version 8. With recent versions like Java 10, a unique version numbering convention is used.

The Java classes defined by Genero (com.fourjs.fgl.lang.*) are compiled with javac -source 1.6 -target 1.6 options. Therefore, the minimum theoretical version is Java SE 6. However, depending on the platform, the minimum required Java version may be greater than version 6.

Note: As a general rule, always install the current long-term-support (LTS) Java version available on your platform, with JNI support. For example, Java SE 8 (released in March 2014) and Java SE 11 (released in September 2018) are LTS versions.

For a detailed list of supported JVMs, refer to the Supported platforms and databases document, available on the Products download page of the Four Js Web site.

The version of the installed Java software can be shown with the command:
java --version

In order to execute Java byte code, the Genero runtime system uses the JNI interface. The JVM is loaded as a shared library and its binary format must match the binary format of the Genero runtime system. For example, a 64-bit Genero package requires a 64-bit JVM.

When implementing Java classes for Genero Mobile for Android (GMA), check the JDK version required by the Android SDK. For more information, see the Android Studio web site.