How to declare a Global variable in Android.

When we need to have several variables across application we can go for global variable. Here I am going to explain, defining global variable by extending the Android's Application class. This is the base class for maintaining global application state.

1) Create a class that extends Application class.

               

public  class  Global extends Application {                                 private Boolean _notification=false;                                 public Boolean get_notification() {                                 return _notification;                                 }                                 public void set_notification(Boolean _notification) {                                  this._notification = _notification;                                 }                 }

2)Add the class to the AndroidManifest file as an attribute of <application> tag:

                               

<application  android:name=".Global"                                 .... />

Android will automatically create an instance of that class and make it available for your entire application.
3) You can access it from any context using the Context.getApplicationContext() method. Now    we can access the global data across the application .like

                              

Global global;                                 public void onCreate(Bundle savedInstanceState) {                                 global=((Global)getApplicationContext());                                 Boolean notification=global.get_notification();}