Versions

[{“Name”:“Java SE 1.1”,“GroupName”:null},{“Name”:“Java SE 1.2”,“GroupName”:null},{“Name”:“Java SE 1.3”,“GroupName”:null},{“Name”:“Java SE 1.4”,“GroupName”:null},{“Name”:“Java SE 5”,“GroupName”:null},{“Name”:“Java SE 6”,“GroupName”:null},{“Name”:“Java SE 7”,“GroupName”:null},{“Name”:“Java SE 8”,“GroupName”:null},{“Name”:“Java SE 9 (Early Access)”,“GroupName”:null}]

Parameters

Parameter | Details |

——— | —–– |

JNIEnv | Pointer to the JNI environment | jobject | The object which invoked the non-static native method | jclass | The class which invoked the static native method |

Remarks

Setting up JNI requires both a Java and a native compiler. Depending on the IDE and OS, there is some setting up required. A guide for Eclipse can be found here. A full tutorial can be found here.

These are the steps for setting up the Java-C++ linkage on windows:

• Compile the Java source files (.java) into classes (.class) using javac.
• Create header (.h) files from the Java classes containing native methods using javah. These files “instruct” the native code which methods it is responsible for implementing.
• Include the header files (#include) in the C++ source files (.cpp) implementing the native methods.
• Compile the C++ source files and create a library (.dll). This library contains the native code implementation.
• Specify the library path (-Djava.library.path) and load it in the Java source file (System.loadLibrary(...)).

Callbacks (Calling Java methods from native code) requires to specify a method descriptor. If the descriptor is incorrect, a runtime error occurs. Because of this, it is helpful to have the descriptors made for us, this can be done with javap -s.