How is this recursive method created in Java?

Exercise $3\mathrm{.}1$ : Recursive Method

Write a 'public void' method $($no return value$)$ named doCall that recursively calls itself $($not static$)$

One integer parameter named num and on the original call it determines how many times doCall executes

Example: doCall$(5)$; should recursively execute $5$ times $($original call plus $4$ recursive calls$).$

You do not call doCall, or initialize num, I will do that. You write a SMALL recursive method