For this tutorial, Groovy should be installed to your pc.
For how to install Groovy and fundamental of Groovy, check here.
If you want to check some java code then no need to write the one complete java class to check you bit code.You can use groovy console to check your java codes.
If you have already configured your groovy bin folder with path then
It will open one window then you can paste your code
String name = "BINOD KUMAR SUMAN";
System.out.println("Name :: "+name);
System.out.println("Now :: "+new Date());
and press Ctrl+R and see your code result on below screen.
Name :: BINOD KUMAR SUMAN
Now :: Sat Jun 12 11:28:02 EEST 2010
Ctrl+W for clear the output. Again you can check your some code. :)