com.jinvoke
Class JInvoke

java.lang.Object
  com.jinvoke.JInvoke

public class JInvoke
extends java.lang.Object

Initializes the J/Invoke runtime for each class importing native methods.

Method Summary

static void

initialize() Initializes all native methods in the caller's class and makes them ready to be called using J/Invoke.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

initialize

public static void initialize()

Initializes all native methods in the caller's class and makes them ready to be called using J/Invoke.

This method must be called once in each class before any native methods marked with the @NativeImport annotation is called. This method binds the native methods annotated with the @NativeImport annotation to the specified exported function in the specified native library (.dll or .so).

A convenient place to call this method is in the static initializer of each class containing @NativeImport annotated native methods.

Example: The following class declares some native methods and calls JInvoke.initialize() from it's static initializer

                import com.jinvoke.JInvoke;
                import com.jinvoke.NativeImport;

                public class User32 {
                    static {
                       JInvoke.initialize();
                    }   

                    @NativeImport(library="User32")
                    public native static int ActivateKeyboardLayout (int hkl, int Flags);

                    @NativeImport(library="User32")
                    public native static boolean AdjustWindowRect (Rect lpRect, int dwStyle, boolean bMenu);

                    // other methods imported from User32.dll

                }
                 

Alternatively, this method can also be called any time prior to 'J/Invoking' a native method, as shown in the example below:

                import com.jinvoke.JInvoke;
                import com.jinvoke.NativeImport;

                public class Example {
                        @NativeImport(library="User32.dll")
                        public static native int MessageBox(int hwnd, String text, String caption, int type);

                        public static void main(String[] args) {
                                JInvoke.initialize();
                                MessageBox(0, "This MessageBox is a native Win32 MessageBox", "Caption", 0);
                        }
                }
                

An UnsatisfiedLinkError will be thrown if a native method (annotated with @NativeImport annotation) is called prior to initializing the containing class using this method.