Operating systems topics

Process, thread differences, PCB, TCB concepts

Deadlocks, scheduling, context switching

Virtual memory, physical memory, paging

Data sections (Text section, data section, BSS, Stack, Heap etc..) – Linker, Compiler jobs

Interrupts, polling, DMA etc..

Memory management, best fit, first fit etc...,

Processors and bus widths (data and address sizes)

Software engineering topics

basic definitions of CMM levels

Software Dev Life Cycle (SDLC) steps (requirements, design, implementation testing etc..)

Water fall, prototype, Iterative

basics of OO concepts (inheritance, encapsulation, asociation, aggregation polymorphism etc..)

Tools used for various phases of SDLC (static, run time analysis tools etc..)

Different kinds of testing (block-box, white-box, unit testing, integration testing etc..)

Android Testing

• JUnit 4 framework and tools provided by Google

Local Unit Tests

• These tests are compiled to run locally on the Java Virtual Machine (JVM) to minimize execution time. Use this approach to run unit tests that have no dependencies on the Android framework.

Instrumented Tests

• runs on an Android device or emulator.
• can be used for unit, user interface (UI), or app component integration testing.

1. Building Instrumented Unit Tests: 
2. Automating User Interface Tests:
• Testing UI for a Single App
• Testing UI for Multiple Apps
3. Testing App Component Integrations: Verify components such as Service, Content Provider

Espresso:  UI testing frameworks, allows you to programmatically simulate user actions and test complex intra-app user interactions.

• can run on devices running Android 2.2 (API level 8) and higher.

Mockito: 

Source: http://developer.android.com/training/testing/start/index.html

Graph - Update In Progress

Dijkstra's algorithm:

• solves the single-source shortest-paths problem in edge-weighted digraphs with non-negative weights using extra space proportional to V and time proportional to E log V (in the worst case).

DAG: (acyclic edge-weighted digraph)

1. Single-source shortest paths: O(E + V)
• solves the single-source problem in linear time.
• handles negative edge weights.
2. Single-source longest paths: O(E + V)

Shortest paths in general edge-weighted digraphs:

• the concept of a shortest path is meaningless if there is a negative cycle.

 Bellman-Ford:

• solves the single-source shortest-paths problem from a given source s
• finds a negative cycle reachable from s
• time proportional to E V and extra space proportional to V

 Floyd-Warshall algorithm:

• Solve all-pairs shortest path problem.
• Time proportional to V^3 and space proportional to V^2

MST(minimum spanning tree)

• A MST of an edge-weighted graph is a spanning tree whose weight (the sum of the weights of its edges) is no larger than the weight of any other spanning tree.
• 
  

RxJava/ RxAndroid

• Sample Code sample which replaces AsyncTaskLoader to load db data

SampleCode

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private void loadDBData() { Observable.defer(new Func0<Observable<List<String>>>() { @Override public Observable<List<String>> call() { Log.d(TAG, "call " + Thread.currentThread().getName()); List<String> stringList = DBHelperUtil.getPasswordEntries(); return Observable.just(stringList); } }) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(this); }

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@Override public void onCompleted() { } @Override public void onError(Throwable e) { } @Override public void onNext(List<String> strings) { }

Working With databinding - TODO

http://prashamtrivedi.github.io/databinding

Securely store user credentials

• security is always a problem with rooted devices. 
• always use encryption to store user’s credentials like User-name/Email Id or passwords
• AES Encyption can be done using below java packages

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

Ex: To Be Updated... 

Popular Opensources used in Android

• AutoFitTextView: A TextView that automatically resizes text to fit perfectly within its bounds ( github )
• android-linear-layout-manager: 
• Barber: https://github.com/hzsweers/barber
• Butterknife: https://github.com/JakeWharton/butterknife
• GoldenGate: https://github.com/Flipboard/GoldenGate
• Material Dialogs: https://github.com/afollestad/material-dialogs
• MaterialEditText: https://github.com/rengwuxian/MaterialEditText
• OkHttp: An HTTP & HTTP/2 client for Android and Java applications. https://github.com/square/okhttp
• Otto: An enhanced Guava-based event bus with emphasis on Android support https://github.com/square/otto
• RxJava: Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM. https://github.com/ReactiveX/RxJava
• RxAndroid: Reactive Extensions for Android https://github.com/ReactiveX/RxAndroid
• StickyListHeaders: an Android library that makes it easy to integrate section headers in your ListView https://github.com/emilsjolander/StickyListHeaders
• VerticalViewPager: https://github.com/castorflex/VerticalViewPager
• zxing: an open-source, multi-format 1D/2D barcode image processing library implemented in Java, with ports to other languages.
• DynamicGrid: Drag and drop GridView for Android.
• HockeySDK: Distribute beta versions, collect live crash reports, get feedback from real users and analyze test coverage.
• TextDrawable: provides images with letter/text
• TokenAutoComplete: Gmail style MultiAutoCompleteTextView for Android
• Rebound: a java library that models spring dynamics. Rebound spring models can be used to create animations that feel natural by introducing real world physics to your application.
• Android-betterpickers: Android library for better Picker DialogFragments https://github.com/code-troopers/android-betterpickers
• android-gif-drawable: Views and Drawable for displaying animated GIFs on Android https://github.com/koral--/android-gif-drawable
• Dagger: A fast dependency injector for Android and Java. https://github.com/square/dagger
• LoganSquare: Screaming fast JSON parsing and serialization library for Android. https://github.com/bluelinelabs/LoganSquare
• ANTLR:
• android-async-http: An asynchronous, callback-based Http client for Android built on top of Apache's HttpClient libraries.
• chat sdk - https://github.com/AppLozic/Applozic-Android-SDK

 

HTTP client vs HttpUrlConnection

Android provides two HTTP clients to perform network operations.

1. Apache HTTP client
2. HttpUrlConnection

Apache HTTP client

• Large and extensive API's
• Supports cookie handling, authentication and connection management
• Suitable for web browser and other web applications
• Does not support HttpResponseCache mechanism, hence leading to increased network usage and battery consumption

HttpURLConnection

• Light weight HTTP client
• Suitable for mobile applications
• Response caching reduce network use, improve speed and save battery.
• HttpURLConnection supported in Android from GB.
• HttpURLConnection is the best choice for Android.