Passing Data Between Activities

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.

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.

How to Launch a new Activity from an Activity?

Intent i = new Intent(this, ActivityTwo.class);startActivity(i);

How to Launch a new Activity from an Activity?

Intent i = new Intent(this, ActivityTwo.class);startActivity(i);

Parm 1: The Context

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.

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.

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

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.

Extracting Data from the IntentIntent 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");int dl = i.getIntExtra("DLNumber", 0);

How to get a result from an Activity

startActivityForResult()• From ActivityOne, you can start ActivityTwo by

calling startActivityForResult(). Using this method, you can specify a request code.

• When ActivityTwo is about to end, you can call setResult() to pass data back to ActivityOne.

• Once ActivityTwo ends, if it called setResult(), then the onActivityResult() method on ActivityOne is executed. ActivityOne can now access the data sent to it from ActivityTwo.

Contacts App

Create an Intent to Launch the Camera AppIn 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.

You want to take a photo?

Activity BActivity A

Contacts App//Code in Activity AIntent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

// start the image capture IntentstartActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

You want to take a photo?

Activity B

Activity A

Contacts App

The contacts app will receive a call in onActivityResult().

When the camera activity completes

Contacts App

When the camera activity completes

//Code in Activity BIntent 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();

Implementing startActivityForResult()

• Code in ActivityOne.java

REQUEST_CODE is a user defined integer. I usually store the REQUEST_CODE as a public static final member so it can be accessed in both activities.

Returning result from SubActivity

Code from ActivityTwo.java

Implementing startActivityForResult()

• Code in ActivityOne.java