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126 Cards in this Set
- Front
- Back
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what was the timeline of major players of early mobile devices? |
Motorola Brick - expensive, big Apple Newton - PDA - tablet and stylus Motorola Marco/Envoy - wireless |
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what was important about the form factor of mobile devices? |
PDAs were large devices palm-sized devices were introduced later, and hand-held form factor became very common |
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what was the role of the telecommunications industry in shaping mobile devices? what's an example of such device and what did it look like and have? |
combined PDA features with networked applications (telnet, phone, fax) / digital cellular telephony Nokia Communicator - clamshell design - qwerty keyboard |
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what are two initial innovations of mobile devices? |
Low-power mobile processors Higher quality displays - gaming and multimedia capable - eased disappearance of hardware keyboard - evolution to multi touch screens |
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what are two initial technologies of mobile devices? |
Low-power, meter-accuracy GPS technologies Embedded sensors |
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what are the 3 new software architectures/native platforms? |
Apple iOS Google Android Microsoft Windows Phone |
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what is android? (composed of two things) |
mobile operating system + app framework |
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what are some multiplatform examples of android/ |
smartwatch TV car systems |
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what is the latest version of Android? what are some of the latest? |
marshmallow (6.0) lollipop, kitkat, jellybean, ice cream sandwich |
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what is android's OS based on, and what is it designed to run on? |
based on linux designed to run on mobile devices |
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what does android's complete application framework allow us to do? |
allows us to create and deploy our own custom apps |
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what are the 4 application components? |
activities services broadcast receivers content providers |
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what things do you put in: res/layout res/menu res/drawable res/raw res/values |
res/layout - XML for layout res/menu - XML for menu specs res/drawable - images res/raw - general purpose files (e.g. audio) res/values - strings, dimensions, styles |
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what is in the AndroidManifest.xml file? |
contains app name, app activities, permissions, etc. |
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what is the Android Device Monitor (DDMS)? |
provides a graphical user interface for several Android application debugging and analysis tools |
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how to log messages with LogCat? |
Log.v(String tag, String message); |
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what is an activity? |
an application component that provides a screen |
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why do we need to know about the activity lifecycle? |
fine-tune behaviour of activity/app - app shouldn't crash when another starts - don't lose user progress - don't lose user data - don't do heavy processing when user is away in another app |
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what is the activity lifecycle? |
onCreate() (or onRestart()) onStart() onResume() onPause() onStop() onDestroy() |
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when logging, what should you keep in mind and what should you do after the app is complete? |
Logging uses memory and CPU resources When app is complete (ready to be released) make sure that you remove the log messages |
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every time device orientation changes, what lifecycle methods get called and what does this mean? |
activity is destroyed and recreated onPause onStop onDestroy onCreate onStart onResume |
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when is onSaveInstanceState() called? (after which method) |
the onSaveInstanceState() method is called each time the activity is paused -> after onPause |
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when is onRestoreInstanceState() called? (after which method) |
Called automatically by the Android system aper onStart() |
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what is bundle? and which two methods share the same bundle as a parameter? |
a map: Key – Value after the system recreates the activity aper destroying it, the onRestoreInstanceState() and onCreate() methods receive the same Bundle |
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how to save things in the bundle? (code) |
in saveinstancestate: outstate.putInt("KEY", value); |
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how to get things from the bundle? (code) |
in onRestoreInstanceState: int retrievedCounter = savedInstanceState.getInt("KEY"); |
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what is the Context class? |
Interface to global information about an application environment |
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what can the application context do? |
- retrieve app resources (strings, images, XML)
- access app preferences - manage private app files and directories - work with app permissions |
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difference between app and system resources |
App resources - defined by the developer within the Android project files and are specific to the application System resources - common resources defined by the Android platform and accessible to all applications through the Android SDK |
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how to reference application resources programmatically? |
using the generated classfilecalled R.java |
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what are the 3 steps in a button click in terms of android system? |
1. button is clicked 2. android system receives event 3. only the listener is interested in reacting to the event |
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what are the 4 steps to implementing button click? |
1. tell android we want to listen to button click - implement View.OnClickListener 2. retrieve button from XML into Java code - findViewById 3. tell java we're listening to button - setOnClickListener 4. create behaviour for what should happen when button is clicked - onClick method |
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what is the difference between a view and a view group? |
view - object, occupies a rectangular area on screen and is responsible for handling events (e.g. button) view group - occupies rectangular area on screen, is invisible and holds other views in a certain structure (vertically, horizontally, grid, etc) |
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what does layout_weight do? what happens if you give something weight 1 and everything else isn't set? |
assign priority or importance to a certain view (more space) if something's set to 1, that will fill up all the space remaining |
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what is LinearLayout? |
viewgroup that stacks items horizontally or vertically |
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difference between layout_gravity and gravity |
layout_gravity is where the item is positioned in its parent gravity is where item is positioned inside itself (doesn't work if it's wrap_content) |
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what can a ListView do? |
Can display large amount of data Manages the data for display on devices of various sizes |
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what are the 3 steps to creating a ListView? |
1. define data source (e.g. array) 2. define listadapter 3. define user interaction - onItemClick |
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what does an adapter do? |
adapter accesses the data and displays it in a view (ListView, GridView, Spinner, etc) |
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what are intents and what do they do? |
Asynchronous messages that allow Android components to request functionality from other components of the Android system |
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what do intent filters do? |
specifies the types of intents that an activity, service, or broadcast receiver can respond to |
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what can intents do in terms of signalling? how do components understand this signalling? |
used to signal the Android system that a certain event has occurred components can register to this event via intent filters |
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what 3 components can intents be sent to? |
activities services broadcast receivers |
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difference between explicit and implicit intents? |
explicit = explicitly define the component which should be called by the Android system, using java class identifier implicit = specify the action which should be performed |
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what are the two methods you need to retrieve result data from the called activity? what's an example? |
startActivityForResult() onActivityResult() e.g. start contacts app to select contact; receive contact details as result |
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what are the 3 types of sensors? give examples |
motion sensors - accelerometer environmental sensors - temperature sensor position sensors - orientation sensor, magnometer |
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guidelines when accessing hardware |
- don't assume hardware exists - always check and verify optional features - exception handling and errors - return value checking - acquire late and release early - do not drain the device battery by misusing hardware resources |
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what 4 classes are part of the sensor framework? what do they do? |
SensorManager - access sensors, register Sensor - instance of sensor with methods that let you determine sensor capabilities SensorEvent - event object provides info like raw data, type of sensor, etc SensorEventListener - interface with 2 callback methods that notifies you when sensor accuracy and values change |
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what are 2 sensor related tasks? |
Identifying sensors and sensor capabilities - disable parts of app that use sensors not present on device - choose optimum sensor for your app Monitor sensor events - get data when sensor changes |
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4 step process in working with sensors |
1. Determine which sensors are available on a device 2. Determine an individual sensor's capabilities, such as its maximum range, manufacturer, power requirements, and resolution 3. Acquire raw sensor data and define the minimum rate at which you acquire sensor data 4. Register and unregister sensor event listeners that monitor sensor changes |
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what are android system services? give examples |
gives you info about the various system components e.g. PowerService gives info about power of system so you can detect low battery e.g. VibrationService allows you to vibrate the phone |
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how to get android system services with code |
PowerManager sm = (PowerManager) getSystemService(Context.POWER_SERVICE); |
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5 types of persistent storage |
SharedPrefs internal storage external storage SQLite database network connection - on the web with network server |
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what are shared prefs? are they private? |
primitive data stored as key/ value pairs private to the app |
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what kind of data can be stored in shared prefs? what are examples of things you would store? |
Only allow primitive data types: boolean, long, int, float, string e.g. store username pasword |
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two methods to access preferences and why use them? |
getPreferences() - just one file getSharedPreferences() - more than one file |
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5 use cases where you'd use preferences |
- store user details - remember last user location - check when app was last updated - store user settings - check if user using app for first time |
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4 steps to using sharedprefs to store data? |
1. get reference to SharedPreferences object - getSharedPreferences() or getPreferences() 2. call editor - edit() 3. use editor to add data with key - putBoolean, putInt 4. commit editor changes - commit() |
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what is SQLite? |
language for managing data in relational databases |
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3 characteristics of app database |
- self-contained - transaction-based - no server |
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3 steps to creating SQLite database schema |
1. define schema (database name, version, table name, column names) 2. create database using queries 3. execute queries (e.g. insert, delete, update) |
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what does the SQLiteOpenHelper class do? 3 things |
- opens database if it exists - creates database if it doesn't exist - updates database as necessary |
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what are the 2 methods that SQLiteOpenHelper has? |
onCreate() - called when db first created onUpgrade() - called whenever db updated |
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how to insert values in database? |
create ContentValues object put key and value into content values e.g. contentValues.put("name", name); db.insert(table name, null, contentValues); |
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what does the query method do? how does it work? what does it return? |
reads data from database pass selection criteria and the desired columns, returns a Cursor |
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what does a cursor object do? |
gives us access to the results returned from a database query allows navigation through the result set |
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what can SimpleCursorAdapter do? what can you specify? |
easy adapter to map columns from a cursor to TextViews or ImageViews defined in an XML file specify which columns you want, which views you want to display the columns, and the XML file that defines the appearance of these views |
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what is a process? what memory space does it run in? |
an executing instance of an application, that runs in its own memory space |
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what is a thread? does it run in its own memory space? |
path of execution within a process threads share the same memory space |
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what is the relationship between a process and a thread? |
one process can be associated with several threads |
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what are the 3 steps of a default process starting? |
1. Application component starts first time 2. Android starts a new process, in a single thread of execution (default) 3. Another component of the app starts (e.g. a service) it will run in the same process and same thread |
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what is the process ranking of termination? |
1. foreground process 2. visible process (e.g. onPause) 3. service process 4. background process 5. empty process |
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4 ways to avoid blocking UI thread |
- don't perform long running operations in main thread - use additional threads for complex tasks - do not modify UI from background threads - use services |
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what is async thread good for? |
tasks lasting between 100ms to a few seconds |
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why use async task? 2 reasons |
easier to implement in comparison to thread and handler automates - creation / termination of background thread - managing of message queues - Updating on progress |
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what are the steps to implement async task |
1. create subclass of AsyncTask 2. Override one or more AsyncTask methods to: - do work in bg thread - handle UI updates in main thread |
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what are async task methods and where do they get called? |
main thread - execute() - onPreExecute() bg thread - doInBackground() - publishProcess() main thread - onProgressUpdate() - onPostExecute() |
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what are the 3 parameters for async task and explain them |
Param - type of parameter sent to the task for exercution Progress - Type of the info used to indicate progress Result - Type of the result received from the background task |
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what are the 2 types of services? |
started - started by app component bound - app binds to it |
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what are uses for service? |
- handle network transactions - play music - interact with content provider - perform file i/o |
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how to create a service? |
1. create subclass of service 2. declare service in manifest 3. override onCreate() and onDestroy() 4. override onBind() for cases when a new component binds to the service after it has been already created 5. activate service from external trigger |
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how does a started service start and stop itself? |
starts when another component calls startService() stops by calling stopSelf() or another component calls stopService() |
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how does a bound service start and stop itself? |
created when another component (client) calls bindService() client closes connection with unbindService() stops when all clients unbind |
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what is webview? |
View that displays web pages/online content in your activity |
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2 ways how can webview be used? |
1. instead of built in browser - provide info like user guide - display documents hosted online 2. application provides data that always requires internet connection to retrieve data - as opposed to performing network request and parsing data to display in Android layout |
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what are the built in webview functionality |
display page navigate forward/back zoom in and out perform searches capture images of page search page for string deal with cookies |
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what are web services |
means of exposing an API over a technology-neutral network endpoint |
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Steps in accessing and capturing data from a web service |
1. check network connection 2. perform network operation in separate thread 3. connect and download data 4. convert data from network into a target data type |
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what is JSON |
javascript object notation way to represent JavaScript objects as Strings |
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when you check network connection (1st step) what 2 methods do you use and what 2 things should you look out for |
getActiveNetworkInfo() isConnected() watch out for: - device maybe out of range of network - user disabled wifi or data |
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in step 2, perform network op in separate thread, what is the process in AsyncTask? |
use AsyncTask in doInBackground(), connect to web service using URL readJSONData() method returns a JSON string with the result from the web service JSON string with the result is provided to the onPostExecute() method |
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in step 3, connect and download data, what do you use to send/receive data and what's the 5 step process? |
HTTPUrlConnection 1. obtain connection by calling URL.openConnection() 2. prepare request 3. transmit data with getInputStream() 4. read response 5. disconnect with disconnect() |
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what is a fragment? |
“Chunks” of UI |
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4 fragment characteristics |
- Small component / portion / chunk of UI - has its own lifecycle - can process its own events - can be added or removed when activity runs |
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2 pros of using fragments |
- combine several fragments in one activity for flexibility and dynamic UI design - accommodate larger screen sizes and portrait/landscape |
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what are the 4 steps to create fragments? |
1. create class for fragment 2. provide layout/appearance for fragment 3. override onCreateView() method to link the layout to the Java class from Step 1 4. use fragment in XML or java |
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what is the fragment lifecycle? |
onAttach() onCreate() onCreateView() onActivityCreated() onStart() onResume() onPause() onSaveInstanceState() onStop() onDestroyView() onDetach() |
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how to add fragment to activity? 2 ways |
XML - static java - add fragment at runtime in response to user interaction |
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what are the 3 steps of fragment transactions? with code |
1. begin transaction - get reference to fragment manager and fragment - instantiate transaction 2. add/remove/replace fragments - transaction.add(R.id.mylayout, frag, "frag"); 3. commit transaction - transaction.commit() |
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why do you need communication between fragments give example |
user performs some interaction on Fragment 1; this interaction will lead to some event happening in Fragment 2 e.g. edit text enter some text, display in textview |
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what's the rule when communicating between fragments and how do you do it |
rule = do not maintain references of one fragment within another fragment create interface with method contain Communicate interface object in frag1, and call the method override method in MainActivity and pass data from frag1 to frag2 |
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what is drag and drop? |
Allow users to move data from one View to another View in the current layout using a graphical drag and drop gesture |
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what are the 5 steps of drag and drop? |
1. user makes gesture 2. app tells system that drag is starting 3. gets representation of data being dragged (drag shadow) 4. system sends drag events to drag listeners, and drag event callbacks associated with view 5. once user releases drag shadow, drag op ends |
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what are the 4 states of drag and drop? |
started - user makes gesture to begin drag continuing - user continues to drag dropped - user releases drag shadow within bounding box of view that can accept it ended - drag operation over |
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what's the drag shadow? how to create? |
the shadow image represents the data being dragged View.DragShadowBuilder |
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5 steps in designing drag/drop operation? |
1. start a drag - create ClipData and DragShadowBuilder - in onTouch 2. respond to events during drag - listeners should react by calling getAction() to figure out action type, and switch - in onDrag 3. handling events during the drag - listeners receive events like location of drag shadow and visibility of listener's view 4. responding to a drop - view previously reported that it could accept the content being dragged - system dispatches a drag event to that View with the action type ACTION_DROP 5. responding to drag end - system sends a drag event to all of the drag event listeners in the activity, with an action type of ACTION_DRAG_ENDED - this says it's over |
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what are the 3 requirements for adding a Google Map into an app? |
1. provide API key in manifest file 2. edit manifest file to integrate google play services 3. check google APK in java with servicesOK() |
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how to display a google map? 2 steps |
create new layout file, which is a fragment setContentView if servicesOK() |
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how to change where we center on the map? XML and java approach |
XML - set camera attributes inside fragment java - gotoLocation(double lat, double lng) method - CameraUpdate |
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what can geocoding do? 2 things |
Pass in lat and lng and get back matching location Pass in city name, postal code or landmark and get back lat and lng |
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what does GeoCoder class do? what are its 2 methods |
Wraps up all request and response functionality, returns everything back to us as a Java object getFromLocation() getFromLocationName() |
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how to use getFromLocation? |
mygeocoder.getFromLocation(Double.parseDouble(latString), Double.parseDouble(lngString)); save that into a list, and then get the first index from the list Address add = list.get(0); add.getLocality(); add.getLongitude(); add.getLatitude(); |
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how to find current location in non-code approach? |
add permissions to manifest ACCESS_COARSE_LOCATION and ACCESS_FINE_LOCATION map.setMyLocationEnabled(true); this shows a button |
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how to find current location in code approach? |
1. add menu item - current location 2. implement GoogleApiClient 3. create location client 4. showCurrentLocation method |
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how does showCurrentLocation method work? |
use getLastLocation method and assign that to a currentLocation object then do same thing with cameraupdate and latlng with currentLocation.getLatitude() etc |
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describe linux kernel layer what's an example |
linux itself and a set of drivers each driver interfaces with some aspect of the Android device e.g. camera driver |
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describe libraries and android runtime layer what's an example of a library |
set of core libraries and a virtual machine (e.g. sqlite database) |
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describe application framework layer and give example |
modules for controlling the different components of an app e.g. activity manager |
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describe application layer and give example |
apps we download, are included, or build ourselves phone |
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what lifecycle methods get called if user launches an app for first time? |
onCreate() onStart() onResume() |
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what are some examples of blocking operations? |
- complex calculations - accessing network resources - accessing local database - parsing data set - accessing content provider |
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what two managers monitor the app for responsiveness? what happens if it's not responsive? |
activity manager window manager if it takes more than 5 seconds, ANR dialog triggered |
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what is the bound service lifecycle? |
call to bindService() onCreate() onBind() onUnbind() onDestroy() |
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what is the started service lifecycle? |
call to startService() onCreate() onStartCommand() onDestroy |
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what are the general service lifecycle callbacks? |
onCreate() onStartCommand() onBind() onDestroy() |
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if a service is bound to an activity and the activity is destroyed or paused, what happens to the service? |
keeps running |
