Can someone explain this java program?

thats the portion that actually reverses the number. say you put in the number 321 into that portion of the code as 'n'. (321 != 0) = true, ret = ret * 10 + ( 321 % 10) = 1. (ret was not initialized, so it defaults to 0). n then goes to 32, 32 still does not = 0, so 1 * 10 + (32%10) = 12, n then = 3, run it one more time to get 123. hope that helps