Android fundamentals

[eldenpark]

procedural programming v. Declarative programming 선언적 프로그래밍

procedural programming 절차적 프로그래밍: 거의 대부분의 절차를 개발자가 정의
선언적 프로그래밍은: 일부만 정의

• why
• how's it related to Android?

three core concepts of android app

• components (5)
• manifest
• resources

android components

• activity
  UI
  AndroidFragments

• Service
  long running operations
  thread vs service
  track the state of operation
  e.g. music player
  monolithic v. modular architecture

• Broadcast receiver
  stateless, onReceive()
  delegate call to another component, e.g. Context.startActivity(), Context.startService()
  listening to system events

• Content providers
  sharing data with other applications as well
  simple key/value pairs => prefer using SharedPreferences
  if having structured data, consider using Database

Last but not least

• application
  Always only a single instance within an application, use this to keep global variables

manifest

• top level element

<manifest/>

• Google Play filters

<uses-feature/>
<supports-screen/>
<uses-sdk/>
<application/>

• Intent filtering
  abstract description of operation
  explicit Intent: know exactly what activity to startActivity
  implicit Intent: only the action
  pending intent*

Resources

<string/>