There is a number of ways to do this but in general it suggests you haven't structured you program correctly. You can do this.
for (int i = 1; i <= n; i++)
getClass().getMethod("method" + i).invoke();
Or you could just have a long method which combines all the functionality you need.
An alternative in Java 8 is to do this
Runnable[] runs = {
this::methodOne,
this::methodTwo,
this::methodThree,
this::methodFour,
this::methodFive,
this::methodSix };
for (int i = 0; i < n; i++)
runs[i].run();