Question

How to pass, at any time!, a boolean field from one activity to a class?

Answer 1

You can create your own singleton class that both your Activity and other class can access at any time. You have to be careful with it because it does add a layer of global variables (which people tend to not like), but it works.

public class MyBoolean{

   private static final MyBoolean instance = new MyBoolean();

   private boolean boolValue = false;

   private MyBoolean(){}

   public static MyBoolean getInstance(){
      return instance;
   }

   public boolean getValue(){
      return boolValue;
   }

   public void setValue(boolean newValue){
      boolValue = newValue;
   }
}

Call MyBoolean.getInstance() and you can use the methods inside which will be in sync with your whole program.