Passing Data Between Activities

1. Passing Data Between Activities

2. Android Activities • If you remember, Android stores Activities on a stack. • You have the ability to add as many Activities onto the stack from you application and needed. • You can also pass data to and from Activities.

3. How to Launch a new Activity from an Activity? • The Activity class provides a method called startActivity() • startActivity() takes an Intent as an argument. • The Intent provides the information with what new Activity we want to create.

4. How to Launch a new Activity from an Activity? Intent i = new Intent(this, ActivityTwo.class); startActivity(i);

5. How to Launch a new Activity from an Activity? Intent i = new Intent(this, ActivityTwo.class); startActivity(i); Parm 1: The Context

6. How to Launch a new Activity from an Activity? Intent i = new Intent(this, ActivityTwo.class); startActivity(i); Parm 2: The Class name of the new Activity to create.

7. Intents • Intents are asynchronous messages which allow Android components to request functionality from other components of the Android system. • In addition to giving information about what Activity we want to launch, Intents can also store data to be passed between Activities.

8. Storing Data in the Intent Intent i = new Intent(this, ActivityTwo.class); i.putExtra("UserName", "John Doe"); i.putExtra("DLNumber", 123456789); startActivity(i);

9. Extracting data stored in Intent from the new Activity • The Activity class has a getIntent() • Use the Intent returned from the getIntent() to extract any data that was passed.

10. Extracting Data from the Intent Intent i = new Intent(this, ActivityTwo.class); i.putExtra("UserName", "John Doe"); i.putExtra("DLNumber", 123456789); startActivity(i); Intent i = getIntent(); String name = i.getStringExtra("UserName"); intdl = i.getIntExtra("DLNumber", 0);

11. How to get a result from an Activity

12. startActivityForResult() • From ActivityOne, you can start ActivityTwo by callingstartActivityForResult(). Using this method, you can specify a request code. • When ActivityTwois about to end, you can call setResult() to pass data back to ActivityOne. • Once ActivityTwoends, if it called setResult(), then the onActivityResult() method on ActivityOne is executed. ActivityOnecan now access the data sent to it from ActivityTwo.

13. You want to take a photo? Activity A Activity B Create an Intent to Launch the Camera App In order to get a picture for a contact. When you start the activity, you’ll send a request code that will be returned to you when the launched activity completes. Contacts App

14. You want to take a photo? Activity A Activity B //Code in Activity A Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); // start the image capture IntentstartActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE); Contacts App

15. When the camera activity completes The contacts app will receive a call in onActivityResult(). Contacts App

16. When the camera activity completes //Code in Activity B Intent intent = new Intent(); intent.putExtra();// It will put an image thumbnail into the intent’s data //set results so Activity A gets onActivityResult() calledsetResult(Activity.RESULT_OK, intent); finish(); Contacts App

17. Implementing startActivityForResult() • Code in ActivityOne.java REQUEST_CODE is a user defined integer. I usually store the REQUEST_CODE as a publicstatic final member so it can be accessed in both activities.

18. Returning result from SubActivity Code from ActivityTwo.java

19. Implementing startActivityForResult() • Code in ActivityOne.java