Kotlin Global Variables (KGV)

Hi bro, I'm confused about how to create a global variable that can maintain its value as long as the application life cycle is still running, meaning as long as the Activity is still running?

Solution

Okay, you can do it by extending the base android.app.Application class and adding some variable getters & setters as follows.

public class MyApplication extends Application {

    private String someVariable;

    public String getSomeVariable() {
        return someVariable;
    }

    public void setSomeVariable(String someVariable) {
        this.someVariable = someVariable;
    }
}

Then, declare the implementation of your class, the tag name will automatically appear in the pop up if you did it correctly when extending the Application base class.

<application
  android:name=".MyApplication"
  android:icon="@drawable/icon"
  android:label="@string/app_name">

So, you can use it in the following way, set (to throw value), get (to get value). You can do it in any Activity.

// set
((MyApplication) this.getApplication()).setSomeVariable("foo");

// get
String s = ((MyApplication) this.getApplication()).getSomeVariable();

Hope it is useful!