How to specify JMX port number dynamically

I am trying to set the port number at which the JMX server starts dynamically through the program. Usually it is done using -Dcom.sun.management.j开发者_开发知识库mxremote.port=1234 (static port), which works fine. Any thoughts on how can it be done dynamically?

System.setProperty("com.sun.management.jmxremote.port", "1234");