Java - how to analyze a function code

We are working with mvc design pattern, where all the data is stored under map.

I want to iterate over all the classes in the system and for each to check what the method is putting on the map and what does the method get from the map.

For example for the next code:

private void myFunc()
{
Object obj = model.get("mykey");
Object obj2 = model.get("mykey2");
.....
model.put("mykey3", "aaa");
}

I want to know that in this function we have 2 gets: mykey and mykey2 and 1 put: mykey3

How can I do it with the code.

Thanks.