How to pass data between Activities in Android?

Consider a scenario after login activity , Sign-out button visible in each activity , now we need to keep session ID available of all activities !!

Solution:

The easiest way to do this would be to pass the session id to the signout activity in the Intent you’re using to
start the activity:

Intent intent = new Intent(getBaseContext(), SignoutActivity.class);
intent.putExtra("EXTRA_SESSION_ID", sessionId);
startActivity(intent);

Access that intent on next activity:

String sessionId = getIntent().getStringExtra("EXTRA_SESSION_ID");

How fragment get context in Android?

You can use getActivity() , which returns the activity associated with a fragment. The activity is a context (since
Activity extends Context ). You can also override the onAttach() method of fragment:

public static class DummySectionFragment extends Fragment{
...
@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
    DBHelper = new DatabaseHelper(activity);
}
}

What is Context on Android ?

The Context class is an Interface to global information about an application environment.

We may assume a Context is a handle to the system; it provides services like resolving resources, obtaining access to databases and preferences, and so on. An Android app has activities. Context is like a handle to the environment your application is currently running in. The activity object inherits the Context object.

Type of Context in android!!

The are mainly two types of context:

  • Application Context: It is an instance that is the singleton and can be accessed in activity via getApplicationContext() . This context is tied to the lifecycle of an application. The application context can be used where you need a context whose lifecycle is separate from the current context or when you are passing a context beyond the scope of activity.
  • Activity Context: This context is tied to the lifecycle of an activity. The activity context should be used when you are passing the context in the scope of an activity or you need the context whose lifecycle is attached to the current context.