Singleton. private variable in the child of the Application class

Question

Singleton. private variable in the child of the Application class

In one of the answers on the forum there are these words:

It is better to create a private variable in the descendant of the Application class with a reference to the instance instead of a private static one in the sigleton class itself, if possible.

I'm confused, I can't understand the difference, please show me the code where everything is done according to this recommendation and the code where the variable is in the class itself.

Well, here is a variable in the class itself, it looks like this:

public class Singleton { 
 private static Singleton instance; 

 private Singleton (){} 

 public static Singleton getInstance(){ 
  if (null == instance){ 
   instance = new Singleton(); 
  } 
  return instance; 
 } 
}

Variable in I don't understand what the Application subclass looks like..Rather, because I do not understand what the benefits will be if you follow this recommendation.

The accepted answer in this question is the subject of my question Singleton in Android-evil?

2

android java singleton

Author: Turalllb, 2018-06-25

Source

1 answers

score 1 · Accepted Answer

Application-the base class for storing the global state of the application. You can use it like this (you need to add android: name=".MyApplication " to the file section AndroidManifest.xml):

public class MyApplication extends Application {
    private String mName;

    @Override
    public void onCreate() {
        super.onCreate();
        setName("Application instance is maintaining global application state");
    }

    public void setName(String name) {
        mName = name;
    }

    public String getName() {
        return mName;
    }
}

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MyApplication myApplication = (MyApplication)getApplication();
        String s = myApplication.getName();
        Log.d("TAG", s);
        myApplication.setName("tester");
        Log.d("TAG", myApplication.getName());
    }
}

However, Google recommends using Singleton:

Note: There is normally no need to subclass Application. In most situations, static singletons can provide the same functionality in a more modular way. If your singleton needs a global context (for example to register broadcast receivers), include Context.getApplicationContext() as a Context argument when invoking your singleton's getInstance() method.

Https://developer.android.com/reference/android/app/Application