Java application to use the maximum available memory in the system

Here you can use the -Xmx and max-heap-size (jnlp) options to set the maximum java application for memory.
If these parameters are not specified, then the system is allowed to use only a small amount of available physical memory. It is for this reason that people play with -Xmx so that the application can use more memory. But for me this is really a nightmare, because the client machine may have different memory, and even the OS should be taken into account.

Is it possible to use a java application to use the maximum available memory in the system?

Thank.