If you want to develop Java code which will run within Vertica as a SQL function, you do have to compile your Java code into a .jar to be loaded into Vertica. For complete directions and examples, see the Vertica "Programmer's Guide" within the "Developing User Defined Functions in Java" section starting on page 593 available at: http://www.vertica.com/documentation/hp-vertica-analytics-platform-7-0-x-product-documentation/
If you want to develop Java code which to run separate from Vertica, but connect with Vertica, use one of the client drivers (such as JDBC) documented starting on page 35 of the same guide.
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If you want to develop Java code which will run within Vertica as a SQL function, you do have to compile your Java code into a .jar to be loaded into Vertica. For complete directions and examples, see the Vertica "Programmer's Guide" within the "Developing User Defined Functions in Java" section starting on page 593 available at: http://www.vertica.com/documentation/hp-vertica-analytics-platform-7-0-x-product-documentation/
If you want to develop Java code which to run separate from Vertica, but connect with Vertica, use one of the client drivers (such as JDBC) documented starting on page 35 of the same guide.