TestNG - running tests from multiple classes in various order

Lets say I have test classes with methods:

Class 1:
 - method 1
 - method 2

Class 2:
 - method 3
 - method 4

What I'd like to accomplish is running tests from different class in such order

 - method 1
 - method 3
 - method 2
 - method 4

Is there easy way to setup testng xml to run tests this way?