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## Step 7: Run the Program

> Now run the Java application (the Main class) with the Java interpreter. You should see the following output:

> >     Hello World!

> If you see an exception like this one:

> >     java.lang.NullPointerException
> >             at java.lang.Runtime.loadLibrary(Runtime.java)
> >             at java.lang.System.loadLibrary(System.java)
> >             at HelloWorld.(HelloWorld.java:5)
> >             at
> >     java.lang.UnsatisfiedLinkError displayHelloWorld
> >             at Main.main(Main.java:3)

> then you don't have a library path set up. The library path is a list of directories that the Java runtime system searches when loading libraries. Set your library path now, and make sure that the name of the directory where the `hello` library lives is in it.

> If you see this exception:

> >     java.lang.UnsatisfiedLinkError no hello in LD_LIBRARY_PATH
> >             at java.lang.Throwable.(Throwable.java)
> >             at java.lang.Error.(Error.java)
> >             at java.lang.LinkageError.(LinkageError.java)
> >             at java.lang.UnsatisfiedLinkError.(UnsatisfiedLinkError.java)
> >             at java.lang.Runtime.loadLibrary(Runtime.java)
> >             at java.lang.System.loadLibrary(System.java)
> >             at HelloWorld.(HelloWorld.java:5)
> >             at
> >     java.lang.UnsatisfiedLinkError displayHelloWorld
> >             at Main.main(Main.java:3)

> then you have a library path set in your environment, but the name of the directory where the `hello` library lives is not in it. Modify your library path, and make sure that the name of the directory where the `hello` library lives is in it.

> Try to run the program again.

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