This would depend on the type of terminal/console your java program runs. You would have to run an external command to achieve this. To run an external command- You can have a look at Runtime.exec(), but before that read this article about how and how not to use exec().
As far as I know, cls in DOS, clrscr(); in C++ are all os dependent.In fact C++ is itself an os-dependent language. This is not the case with java. java uses bytecode logic(Google if you would like to know more) and thus is os-independent and hence doesnot allow os-dependent commands.
A simple means of clearing the screen is