Returning the update value of variable initialized in a method (Android Studio) : I'm new to programming so please bare with me.

I have three methods. Method 1, Method 2 and Method 3.

Each of these methods contain a String variable which is initailized within the method. Note: These methods are called when a user clicks on a button, so in other words theres a click listener.

Now in the main method, what i want to do, is create a 4th String variable, which is initialized as such:

    public class Main{
       
     String Variable4 = variable1 + variable2 + variable 3
        System.out.println(Variable4);
    }

The problem however is, variable 4 is null. And this is because the variables in the 3 methods are null in the main method. But they are initialized locally in the methods.

So how would I return the initialized variable in the main method?

Apologies for the long question