Ian Darwin - Everybody knows that you have to write Android apps in Java, right? Wrong!

This session will cover a variety of technologies that let you build and package Android apps without writing a line of Java code. Technologies covered will include App Inventor - a simple visual building-blocks approach - and focus on well-known other languages (including Python, Perl, and a cast of other scripting languages mentioned in passing), and of course that old favorite C and its overgrown offspring C++. Not to mention OpenGL and some physics and gaming frameworks like Cocos2D.

Transcript

1. Android App Dev for Non-Java Devs Ian Darwin University Health Network Centre for Global eHealth Innovation http:/ /ehealthinnovation.org O’Reilly Android Cookbook http:/ /androidcookbook.com/ 1 Thursday, 17 October, 13
2. Ian Darwin ian@darwinsys.com • Android Cookbook: androidcookbook.com, O'Reilly, Amazon, .. • Most of the contributed code samples in that book are in Java(!) and are free on github.com/ AndroidCook/Android-Cookbook-Examples repo •One subdirectory per demo project 2 Thursday, 17 October, 13
3. Got Code? 3 Thursday, 17 October, 13
4. Android: It’s not just for Java Devs anymore! • App Inventor • SL4a (gives Python, Perl, and more) • Ruboto (gives Ruby) • HTML5 (phonegap, Cocos2D, etc) • Other Languages (C++, Scheme, Clojure, ...) 4 Thursday, 17 October, 13
5. Part 1: App Inventor 5 Thursday, 17 October, 13
6. App Inventor • Invented by Google, using MIT technologies, Open sourced, trademark handed over to MIT • Uses drag-and-building-blocks metaphor • Does most of what "standard" SDK can do • Encourages non-programmers to get involved in building mobile apps! –See the app on your phone as you build it 6 Thursday, 17 October, 13
7. Starting With App Inventor • http:/ /Explore.AppInventor.MIT.Edu –Tutorials, examples, curricula, and non-obvious setup instructions • Must have Java 6 enabled in browser • Must run Setup installer on local computer • Then login with your Google/GMail account –Apps updatable from any computer; only testable if Setup run there 7 Thursday, 17 October, 13
8. Setup - Mandatory 8 Thursday, 17 October, 13
9. Inventing An App • First page shows Drag-and-drop GUI Builder • Open Blocks Editor button to add event handling • Then run on Emulator or real device over USB • Then package as APK and sell on Google Play app store 9 Thursday, 17 October, 13
10. Inventing the GUI 10 Thursday, 17 October, 13
11. Adding Actions: Blocks Editor 11 Thursday, 17 October, 13
12. App Inventor Summary • App Inventor looks easy • Takes a while to find things - read the tutorial before ploughing in! • This can be good for non-technical people •If the navigation is explained well 12 Thursday, 17 October, 13
13. Part 2: Scripting Layer for Android (SL4A) 13 Thursday, 17 October, 13
14. SL4A • SL4a allows an open-ended number of scripting languages to be used • Already: Python (2.6) Perl JRuby sh/bash lua BeanShell Tcl JavaScript(Rhino) • Not in Play Store, must download • http:/ /code.google.com/p/android-scripting/ • After downloading, then must add interpreter(s) • Hidden: Menu->View->Interpreters->Add • For Perl and Python, there are forked projects to simplify download 14 Thursday, 17 October, 13
15. 15 Thursday, 17 October, 13
16. SL4A API • Get an "Android" object • Everything starts from there. • Huge API • http:/ /code.google.com/p/android- scripting/wiki/ApiReference 16 Thursday, 17 October, 13
17. hello.py • $ more hello_world.py • import android • droid = android.Android() • droid.makeToast('Hello, Android!') 17 Thursday, 17 October, 13
18. sms.py droid = android.Android() number = ‘647-555-5555’ message = ‘Hello via sms’ stat = droid.smsSend(number, message); 18 Thursday, 17 October, 13
19. Managing Scripts • Script editing tedious - it aint vi/emacs • Intended for on-device experimentation • Try keeping in CVS/SVN/Git and copying •adb push/pull • Better - native version control client? 19 Thursday, 17 October, 13
20. phonepicker.py import android d = android.Android() num = d.pickPhone().result d.phoneCallNumber(num) 20 Thursday, 17 October, 13
21. ifconfig.py • Runs netcfg, extracts external ip address ifs = {} r=r'^(\w+\d?)\s+(UP|DOWN)\s+([\d.]+).*' proc = os.popen('netcfg','r') for line in proc.readlines(): m=re.match(r, line) if m and m.group(1) != 'lo' and m.group(2)=='UP': ifname=m.group(1) ipaddr=m.group(3) ifs[ifname] = ipaddr # droid.makeToast(str(ifs)) title = 'ifconfig output' message = str(ifs) droid.dialogCreateAlert(title, message) droid.dialogSetPositiveButtonText('Happy now!') droid.dialogShow() response = droid.dialogGetResponse().result 21 Thursday, 17 October, 13
22. speak.py • Built-in TTS message = ... droid.ttsSpeak(message) 22 Thursday, 17 October, 13
23. Longer Examples.py See test.py - exercises many bits of API See “Judge Droid”, start at cloning Locale! http:/ /www.morelightmorelight.com/ 2010/04/05/judge-droid-lays-down- the-law/ 23 Thursday, 17 October, 13
24. Perl 5.10 Examples • Basically same API but with Perl syntax • e.g. Speaking: • my $result = $droid->ttsSpeak(message); • Compare test.py and test.pl in the googlecode downloads 24 Thursday, 17 October, 13
25. APK how-to • Manual method •create project, copy interpreter, etc. • Python, Perl Projects: • http:/ /code.google.com/p/android- python27 / • http:/ /code.google.com/p/perl-android- apk/ 25 Thursday, 17 October, 13
26. Sharing Your Script • In Qr Code - they’re not just for URLs!! • Visit http:// zxing.appspot.com/ generator/ • Set mode to text, size to Large • Put default script name as first line • Paste your script, click Generate and it’s done! • As APK https:/ /androidcookbook.com/r/2916 26 Thursday, 17 October, 13
27. What would a Java geek coming to Android want? Standard Java includes javax.scripting that lets you do all that from within Java app If Android had this, nirvana? A partial implementation actually exists, using V8 JS engine, at https:/ / code.google.com/p/jav8/ 27 Thursday, 17 October, 13
28. Part 3: Ruboto 28 Thursday, 17 October, 13
29. Ruboto - Ruby for the Robot? • Based on JRuby • 1) Ruboto-irb is an Interactive Ruby app (in the Play Store). •Has own script editor • 2) Main Ruboto runs on desktop PC, builds apks –Requires Ruboto Core installed on device 29 Thursday, 17 October, 13
30. Ruboto API More like “standard” Android API Activity class: Define methods like on_create, on_resume as per Android api 30 Thursday, 17 October, 13
31. Hello Ruboto # # Hello, World (imports omitted!) # def self.hello_world(context) java_import "android.view.Gravity" ruboto_import_widgets :TextView context.start_ruboto_activity "$hello_world" do setTitle "App/Activity/Hello World" def on_create(bundle) setContentView(text_view :text => "Hello, World!", :gravity => (Gravity::CENTER_HORIZONTAL | Gravity::CENTER_VERTICAL)) end end end 31 Thursday, 17 October, 13
32. $activity.start_ruboto_activity "$glsurface" do setTitle "GLSurfaceView" def on_create(bundle) @surface_view = TouchSurfaceView.new(self) @surface_view.renderer = RubotoGLSurfaceViewRenderer.new self.content_view = @surface_view end def on_resume @surface_view.on_resume end ... end Fraction of OpenGL demo 32 Thursday, 17 October, 13
33. Part 4: HTML5 33 Thursday, 17 October, 13
34. HTML5: Phonegap/ Cordova Topic has been done to death! Write a mobile web app Package with PhoneGap a.k.a. Cordova Pro - gets you other platforms Cons - hard to look native Covered in other sessions at most conferences! 34 Thursday, 17 October, 13
35. HTML5 + Cocos2D Cocos2D is two frameworks, one for C++ and one for HTML5 Both multi-platform Both include other scripting langs Lua See http:/ /www.cocos2d-x.org 35 Thursday, 17 October, 13
36. Cocos2Dx Code? No code example since - being C++ - you need about 10 files to run “Hello World” 5 in your app, 5 in proj.mac, more in proj.android, more in proj.blackberry, etc XCode built hello app for Mac; Android version failed the “5 minute test” - did not build on my test system 36 Thursday, 17 October, 13
37. 37 Thursday, 17 October, 13
38. PART 5: /otherlangs 38 Thursday, 17 October, 13
39. And the lord divided them, and gave them all different languages... • C/C++ - NDK • Scheme (Kawa) • Scala • Clojure • You name it... 39 Thursday, 17 October, 13
40. NDK Call C or C++ from Java - same as SE public native foo(int bar); static {System.loadLibrary(“bar”);} Compile, run javah, implement C code defined in header Build Makefile fragments tell Make to build bar.so, install in apk 40 Thursday, 17 October, 13
41. package foo.ndkdemo; public class Main { static { System.loadLibrary("sqrt-demo"); } public static native double sqrtInC(double d); $ cat jni/sqrt-demo.c #include <stdio.h> #include <stdlib.h> #include "foo_ndkdemo_SqrtDemo.h" JNIEXPORT jdouble JNICALL Java_foo_ndkdemo_SqrtDemo_sqrtInC( JNIEnv *env, jclass clazz, jdouble d) { jdouble x0 = 10.0, x1 = d, diff; do { x1 = x0 - (((x0 * x0) - d) / (x0 * 2)); diff = x1 - x0; // printf("x0=%12.8f, x1=%12.8f, diff=%12.8f\n", // x0, x1, diff); x0 = x1; } while (labs(diff) > foo_ndkdemo_SqrtDemo_EPSILON); return x1; } 41 Thursday, 17 October, 13
42. C++: All OpenGL Games commonly provide entire UI in OpenGL, app logic in C/C++ Supported by Android (NDK or NativeActivity), iOS, BB10 (and probably everything else) Good performance, reasonable portability Good for “games-like” UI; not for “standard” interactive app (lists) 42 Thursday, 17 October, 13
43. Android NativeActivity Android lifecycle (onCreate(), onResume() etc.) not smooth fit for OpenGL lifecycle (init, resize, display) They provide android_native_app_glue and an Android-specific lifecycle, running own thread See http:/ /developer.android.com/tools/ sdk/ndk/; example at http:/ / developer.android.com/reference/ android/app/NativeActivity.html 43 Thursday, 17 October, 13
44. C++ + GUI Toolkit QT Toolkit covers more than just GUI Widely used in open source (KDE) and is the base for BB10 GUI! But: BB “Cascades” widgets BB10-only Projects adapting QT to platforms e.g., “Necessitas” = QT for Android Like Android: XML layouts and GUI builder (We need FOSS “qml to Android XML”) 44 Thursday, 17 October, 13
45. C++ + Tooling: MoSync MoSync provides Eclipse-based IDE, open source tools for: C++ app gen, app runs on many platforms (widest range of any?) JavaScript No server dependencies (unlike competing projects) 45 Thursday, 17 October, 13
46. C++ + Tooling: MoSync MoSync provides Eclipse-based IDE, open source tools for: C++ app gen, app runs on many platforms (widest range of any?) JavaScript No server dependencies (unlike competing projects) 45 Thursday, 17 October, 13
47. Kawa Scheme Web site documents its use It is used in App Inventor We found it difficult to install http:/ /per.bothner.com/blog/2010/ AndroidHelloScheme/ http:/ /androidscheme.blogspot.ca/ 46 Thursday, 17 October, 13
48. Scala Scala is a JVM language that tries to be “ a better Java” introducing Functional Programming http:/ /robots.thoughtbot.com/post/ 5836463058/scala-a-better-java-for- android 47 Thursday, 17 October, 13
49. package com.thoughtbot.helloscala import _root_.android.app.Activity import _root_.android.os.Bundle import _root_.android.widget.Toast import _root_.android.view.View import _root_.android.view.View.OnClickListener import _root_.android.widget.Button class HelloActivity extends Activity { override def onCreate(savedInstanceState : Bundle) { super.onCreate(savedInstanceState) setContentView(R.layout.main) val button = findViewById(R.id.button).asInstanceOf[Button] button.setOnClickListener(new View.OnClickListener() { def onClick(v : View) { Toast.makeText(this, "You have clicked the button", Toast.LENGTH_LONG).show() } }) } } Hello.scala This is Java-like style Scala people prefer traits and implicits (similar to AOP?) See web page for better example!! 48 Thursday, 17 October, 13
50. Clojure A Lisp-1 language for the JVM with full Java integration Android support at http:/ /clojure- android.blogspot.ca/ 49 Thursday, 17 October, 13
51. Others Are there other languages? Undoubtedly Do I have time to track them all down? No AndroidCookbook.com is crowdsourced; add your favorite! 50 Thursday, 17 October, 13
52. obPlug: http:/ /androidcookbook.com/ 51 Thursday, 17 October, 13
53. References- Other Books Android Design Patterns book (Nudelman) APress Android Games books (OpenGL) Robert Green Infinite # of books on: Android, iOS, x-plat, PhoneGap, etc etc... 52 Thursday, 17 October, 13
54. Code Samples Colin Eberhardt’s PropertyCross project implements a realistic app (Real Estate Property Search) in several platforms Open-source Tries to measure code sharing too 53 Thursday, 17 October, 13
55. Code Samples Colin Eberhardt’s PropertyCross project implements a realistic app (Real Estate Property Search) in several platforms Open-source Tries to measure code sharing too 53 Thursday, 17 October, 13
56. Q & A • Ian Darwin ian@darwinsys.com 54 Thursday, 17 October, 13