INPUT: an integer number n>=0

But what is n? Number of sides? Friend's best score?

Why in the example do you need to roll 1 thrice in order to win (or lose)? Doesn't the highest single number win?

Please clarify some of these points, preferrably in description.

But he does not know the probabilities for finding a certain number m.

Make this "But he does not know the probabilities for finding a certain number."

There is no need to introduce a variable name here, let alone a new one that is then never used again.

the probability to get the number n is 1/2^n.

INPUT: an integer number n>=0

Don't give different variables identical names. ( An argument doesn't even need a specified name! )

Note: ./src/test/java/SwapTest.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.