EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E
Programming Mobile Applications for Android
Adam Porter, University of Maryland
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C O U R S E L E C T U R E Android Architecture Notes taken on June 10, 2014 by Edward Tanguay |
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android platform
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software stack to support phones and tablets
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has several layers software from the low-level OS kernel up to key apps
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comes from SDK
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Android Architecture
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Linux Kernal
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lowest layer of software
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provides core services
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permissions
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memory and process management
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file and network I/O
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device drivers
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Android specific services
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power management (for increased battery power)
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shared memory
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low memory killer
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interprocess communication mechanism (Binder IPC Mechanism)
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Libraries
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typically written in C and C++, hence referred to as the "native libraries"
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System C library
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process and thread creation
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mathematical computations
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Surface Manager
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updating the display
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Media Framwork
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audio/video
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Webkit
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rendering web pages
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OpenGL
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high performance graphics
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SQLIte
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in memory relational databaes
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Android Runtime
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Core Java Libraries
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Android applications are typically written in the Java programming language
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basic classes
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java.* and javax.* classes
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app lifecycle
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android.*
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Internet/Web services
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ord.*
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unit testing
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junit.*
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Dalvik Virtual Machine
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the software that actually executes Android applications
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Android apps are written in Java but they do not run on a standard Java virtual machine
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develop first write their applications in Java
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the compile turns it into bytecode files
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tool called dx transfomed the bytecode files into classes.dex
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classes.dex is packaged with other application resources and installed on the device
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when use launches the app, the Dalvic Virtual Machine will execute the classes.dex file
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designed to run in resource constraained environment
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lower CPU
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less memory
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limited battery life
Dan Bornstein (Google) on the Dalvik Virtual Machine (2008)
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Application Framework
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reusable software that modbile applications need
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package manager
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database that keeps track of all applications installed on device
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windows manager
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manages windows of an app
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system notification bar
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main app window
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sub windows of menus or dialogues
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view system
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icons
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text entry boxes
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buttons
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Resource manager
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lets you define strings in multiple languages
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Activity Manager
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coordinate activities
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e.g. hit back button and go to last activity
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Content Providers
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inter-app data sharing
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e.g. use contact information in a content provider
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Location Manager
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allows applications to receive location and movement information
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Notification Manager
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software always listing for incoming notifications and put a notice in message bar
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Applications
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Home Screen
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Contacts
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none of the standard apps are hard-coded into the system