SQL> create or replace and compile java source named "GetVersion" as
   2   public class GetVersion
   3   {
   4     public static void printVersion()
   5     {
   6       String ver;
   7       ver = System.getProperty("java.version");
   8       System.out.println("The JDK version is " + ver);
   9     }
  10   }
  11   /

Java created.

SQL> create or replace procedure Get_JDK_Version is language java
   2   name 'GetVersion.printVersion()';
   3   /

Procedure created.

SQL> set serveroutput on
SQL> call dbms_java.set_output( 1000 );

Call completed.

SQL> exec Get_JDK_Version;
The JDK version is  1 . 4 .2_04

PL/SQL procedure successfully completed.

SQL>