andrew@theinternet

Software Dev Process Lecture Notes - Part 2 Lesson 3 - Android

Android Programming

• Android runs in Dalvik VM. Runtime for Java, optimized for mobile
• Basic architecture (descending order)

Activities

• A single screen with a UI (e.g. phone dialer)
• Independent units, work together to form a cohesive whole
• Create an activity by extending the Activity class in the Android framework

Services

• A component that performas a usually long-running activity in the background, not interacting with the user.
  • No UI, obviously
• Create a service by extending the Service class in the Android framework
• A way to tell the system something needs to keep happening even if app is closed

Content Provider

• provides a structured interface to a set of data
• sqlite data is android setup for database. frequently this is where you tie to with content provider
• sometimes also used by app to share data with other apps
  • e.g. address book / contacts app sharing with other apps that want it

Broadcast Receiver

• Receiver that can be registered to receive system or application events
• sounds like a ‘listener’ to me

Intents

• Connect above components
• Abstract description of an operation to be performed
• consists of 2 main parts
  1. action to be performed (e.g. “call”)
  2. data action operates on (e.g. “phone number”)
• Provide developers with a way to perform late binding between applications at runtime
• How can this be done?
  • Binding
    1. direct(activity)
    2. direct(service)
    3. broadcast (delivered to all receivers)
       • this is why when you click a phone number you have to pick which app takes it. you broadcasted a call intent and each receiver chimed in that it could take it

Manifests

• An XML file that declares all of the components of your app (broadcast receivers can be declared either here or at runtime)
• All the permissions required for your app to work
• Specifies the entry point for your app (which activity must be started to start the app)
• Declares version of the app
• Declares the lowest Android SDK for which the app is valid

Android Activity Lifecycle

• Apps get interrupted all the time. Apps must be able to deal with this. Gracefully if possible.