How to Access Android Custom Application Object in simple Java Class which Also has ApplicationContext object?

Question

I have created a custom application class like this:

class A extends android.app.Application{
    public String abc  = "xyz";
}

And I have a simple java class

class B {
     private appContext;

     // This constructor is called from activity.
     B(Context ctx){
         this.appContext = ctx;
     }

     private void foo(){
          // want to access Class A's abc String vairable Here...HOW TO DO THAT?????
     }
}

How to access Class A's abc String vairable in foo method.

Answer 1

You can get the Application class with getApplicationContext from Context with the good casting

((A) this.ctx.getApplicationContext()).abc;

Answer 2

The Application class in Android is a singleton and therefore so is your derived class. Android will create just one instance of your class A when it starts your application. Just change

class A extends android.app.Application {
    public String abc  = "xyz";
}

to

class A extends android.app.Application {
    public static String abc = "xyz";
}

and you can reference it from anywhere like this:

String foo = A.abc;