day 4: android: getting active through activities

Android Application DevelopmentBeing Active Through Activities & Intents

Ahsanul Karim ahsanul.karim@sentinelbd.com

Sentinel Solutions Ltd.http://www.sentinelbd.com

Today We’re Covering…

• Application Structure• Android Application Anatomy• Activity• Layout• Using Layouts from Activity• Activity to Activity Transition• Activity Lifecycle• Exercise

Android ActivitiesActivityActivity provides a user generally with an interactive screen to do something like: Dialing the phone, View a map List of something for user to select or Anything you want your user to do

• An application usually consists of multiple activities.• Typically, one activity in an application is specified as the "main" activity,

which is presented to the user when launching the application for the first time. (which is specified in AndroidMenifest.xml)

The <action> element specifies that this is the "main" entry point to the application. The <category> element specifies that this activity should be listed in the system's application launcher (to allow users to launch this activity).

Android Activities (Contd..)Creating ActivityWe have already created Activities. But how did we create it?Let’s revisit…

1. We created subclass of Activity base class2. We implemented one callback method onCreate

1. What is creating subclass???2. What is callback methods???

Open Questions:

Android Activities (Contd..)Next Step: Implementing User Interface

1. Design res/layout/yourlayout.xml2. Use Views from Activity class

Next Step: Implementing User Interface<manifest ... > <application ... > <activity android:name=".ExampleActivity" /> ... </application ... > ...</manifest >

Next Step: Starting Activity

Intent intent = new Intent(this, ToActivity.class);startActivity(intent);

We can start another activity by calling startActivity(), passing it an Intent that describes the activity you want to start.

Android Activities Exercise1. We’ll make 2 Activities2. Registration with basic features and validation:

1. Email address2. First Name, Last Name3. Date of Birth4. Password5. Confirm Password6. I agree to terms and conditions7. Buttons: Cancel, Submit

3. Login1. Email address2. Password3. Buttons: New User, Login(To be added: Remember me)

Link: http://developer.android.com/guide/appendix/faq/commontasks.html

Android Activities Exercise (Contd.)1. How to add new Activities to the application2. How to navigate from one Activity to another

How to navigate from one Activity to another

Intent

Intent intent_1_to_2 = new Intent(this, Activity2.class);startActivity(intent_1_to_2);

Intent

Intent intent_2_to_1 = new Intent(this, Activity1.class);startActivity(intent_2_to_1);

Android Activities Exercise (Contd.)How to navigate from one Activity to another

Intent

Intent intent1to2 = new Intent(this, Activity2.class);startActivity(intent1to2);

Intent

Intent intent2to1 = new Intent(this, Activity1.class);startActivity(intent2to1);

Activity Lifecycle

Activity Lifecycle (Contd.)