Create Java Plugin for Unity

I'm developing an android application using Unity and want to hide the bottom bar when running my application. So I am going to create a java plugin and have reference from this link

I have Eclipse installed but not sure how to start. What kind of project I have to create? Java Project? Android Application Project? Plugin-In Project?

Here is the code I am going to place:

     View sb = getWindow().getDecorView();
     sb.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);

Thanks for help