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Trail: Java Native Interface
Lesson: Writing a Java Program with Native Methods

## Step 5: Create a Shared Library

> Remember in Step 1: Write the Java Code you used the following method call to load a shared library named `hello` into your program at runtime:

> >     System.loadLibrary("hello");

> Now you are ready to create this shared library.

> In the previous step, Step 4: Write the Native Method Implementation, you created a C file in which you wrote the implementation for the `displayHelloWorld` native method. You saved the native method in the file `HelloWorldImp.c`. Now, you must compile `HelloWorldImp.c` into a shared library, which you name `hello` to match the library name used in the `System.loadLibrary` method.

> Compile the native language code that you created in the previous two steps into a shared library. On Solaris, you'll create a shared library, while on Windows 95/NT you'll create a dynamic link library (DLL). Remember to specify the path or paths to all necessary header files. See Creating and Loading Shared Libraries for information on forming a shared library name.

> On Solaris, the following command builds a shared library `libhello.so`:

> >     cc -G -I/usr/local/java/include -I/usr/local/java/include/solaris \
> >           HelloWorldImp.c -o libhello.so

> On Win32, the following command builds a dynamic link library `hello.dll` using Microsoft Visual C++ 4.0:

> >     cl -Ic:\java\include -Ic:\java\include\win32
> >           -LD HelloWorldImp.c -Fehello.dll

> Of course, you need to specify the `include` path that corresponds to the setup on your own machine.

> For more information on the system-dependent mechanisms for loading a shared library, see Creating and Loading Shared Libraries.

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