Android Studio global static variable accessible from multiple activities

Question

In android studio I want to have a static (unchanging) variable which, I can obtain from multiple activities. My application has several activities:

1. Login Activity
2. Home Activity
3. Sub Activity 1
4. Sub Activity 2
5. Sub Activity 3

Within these activities I need to check a value to execute different code depending on the value. In my case it is a device address. I use this device address in two places and therefore, presently define it in 2 separate places. I know this is an incorrect way of doing this. So I want to define it once and access it from both activities e.g. Home Activity and Sub Activity 1.

I want to know where I can define this variable and then how I include it. An example of the variable is : private String Device_Address = "XX:XX:XX:XX:XX:XX";

One idea is should I make it a public static variable from the home activity and then import the variable to the sub activity?

Thanks

Answer 1

Declare veriable in Application class

public class App extends Application
{
   private boolean isActive= false;

 public boolean getisActive() {
        return isActive;
    }

    public void setisActive(boolean _isActive) {
        this.isActive= _isActive;
    }

}

and Usage is

App.getInstance().getisActive()

Register App in Manifest

<application
        android:name=".App"