Develop Reference

java applet to android workflow

I have built an interactive taxonomic key and the output is a java applet. I want to covert it onto an app that can be used locally ie on phone for example with no connection to the internet (its important as people on project are working in remote locations).
My question is can I edit the java applet in Android studio? Willing to learn just want to know what the best approach is. later would need to work on it being available on IOS devices too.
Thanks, Amanda

Java applets and Android apps have nothing in common with each other, other than language. The UI and input frameworks are totally different. You could share some of the logic of the app if you put it into a jar file, but you won't be able to share anything else. And Java doesn't run on iOS, so that's totally out.
Also, not sure why you tagged this javascript. Java and javascript are totally different languages. A Java applet has nothing to do with javascript.

Multiplatform app development with individual guis

I am currently planning the development of a multiplatform app, and I am not sure wich way to do it fits my requirements best, since all possibilties I could think of failed to satisfy me.
First I want to write an app for android, which should feel like a normal typical android app. So I want to use the standard actionbar and android design look and feel in my other gui elements. After finishing the android app I am planning on developing an ios app, which should have a different design, so i am going to redevelop the gui for this anyway.
But I don´t want to rewrite the other code wich represents the intelligence of the app, independent from the gui. I came up with the following possibilities:
1. Java GUI With native library
Here I abstract all the code of my app in a C++ library (since as far as I know ios supports the usage of c++ libraries too) and develop the gui android typically in java. The library would than have a function to start and would inform the gui about every change via callback functions.
Pro
I can reuse all the code that would be the same on both platforms. I just would implement the gui seperately
The design of the android gui is straightforward as I want it to be. It looks like typical android because it is typical android.
Cons
I dislike the usage of JNI very much. Especially the signature and names of the callback functions (calling java functions from c++) are not checked at compile time and require a lot of manual work. If I rename a function and forget to rework the native part I only notice this mistake at runtime.
2. Build the GUI on the native side
Here I had difficulties finding out what is possible, especially for 2.2
2.1 Use Qt
I have only a few first step experiences with Qt in general but as far as I understood i would have the following pros and cons:
Pro
Reuse most parts of the code for ios and Android. I would than redesign the gui for each platform to make them feel natural. I can´t evaluate how much qt may even assists me at doing that
Cons
I have to copy the android gui by using other qt widgets. This is more effort and I don´t know if one can replicate the android gui elements (like the actionbar) so that the user wouldn´t notice it.
2.2 Using the android framework from the native side
I dont know if this is possible at all, I wasn´t able to find this information. Can I use the class "NativeActivity" and use the android framework to build the gui and use e.g. the actionbar? If this is possible somehow it would have the pros from 1. and maybe wouldn´t have it cons?
Do you have any feedback to my ideas or maybe even new approaches I didn´t think of? How do other multiplatform apps like WhatsApp solve this problem? Do they have redundant code for each platform?
Thank you,
Tobi

I would say that it depends very much on your application requirements. By my opinion, a better solution is to develop a separate application for each platform using recommended SDK's for that platform, and implement in native C++ only the time consuming data processing algorithms.
Application runtime on mobile platforms is not so straightforward as on desktop platforms. You should take into account background and foreground processing, specific application life cycling, accessing system resources such as network, file system, etc. And all these issues do differ on iOS and Android.
Regarding possibilities that you listed.
Qt/QML is ok only in case two requirements are met:
1.1 Your application is a foregroud application without any background operations.
1.2 You purchase a commercial Qt license because only commercial Qt can be submitted to Apple iTunes app store (even GPL apps are under
question).
Using NDK Native Activities on Android with cross-platform C/C++ backend. Android NDK API offers much less API then Android Java SDK, so a lot of things you will have to implement or wrap manually. It is a hard road.
Mixing Java code and C/C++ using JNI gives you more of Android SDK API. But you should remember that an Android activity's life cycle is not somewhat that you're used to deal with when developing on C/C++.
Approach that we are using
We've been developing an application with a huge amount of cross platform functionality that should work on Windows/Linux/Mac OSx/Android/iOS. We're using the approach as follows.
Cross-platform core is written in pure C++.
We have adaptors to GUI interface for each platform.
On desktop we use Qt as it reaches all desktop platforms with minor adapting to each platform.
On iOS the GUI is built using iOS SDK with Objective-C and C++ core is linked as a Framework. Still, we had to patch our core in some way for iOS background requirements and so.
On Android we wrap our C++ core in a background process and build all the GUI using only Android Java SDK. Foreground GUI activities interact with the core via local sockets, so we don't need to bother with activities life cycling in our C++ core. But the adaptor is a litle bit complicated.
Nevertheless, both mobile platforms often require workarounds and adaptations in C++ core which add a number of #ifdef'ed branches in code for each platform.

Does Android Studio supports AngularJS for Android UI design?

I have a question about Android Studio: Does AS supports AngularJS code while designing XML files, e.g. for small animations or effects?

SUMMARY : NO
There is no way you can write Angular JS code while developing Android Native app. You can use Angular in a WebView (using js/html so), that's all.

AngularJS is a completely different technology than what is used in native Android apps. Native Android apps use Java and/or C for their code, which is compiled when you build the app. AngularJS is a framework for web development, running specifically on Javascript (a completely different technology than Java).
You can build apps without using native Java or C code, but there are tradeoffs. As noted in other answers, you can display webpage views as apps (using technologies like Cordova]), or use frameworks like React Native to write code in Javascript that then gets compiled to a native app. You could use AngluarJS in the webview instance, since it just displays a webpage, however not in something like React Native. I highly encourage you to check both of these (and other options) out, but keep in mind that they have their own limitations and tradeoffs – no one way is the "right" way to build an app.
In summary: No, AngularJS is a web technology, not a native app technology.

new answer = Yes... Sort of, you can do it with:
https://www.nativescript.org/
It translates javascript, angular and typescript code into native components!
Apparantly it's possible to use nativescript in Android Studio with:
https://docs.nativescript.org/runtimes/android/getting-started/hello-world

Android Does not support AngularJs. but still if you want to use you can use it in webview.

Android Cross-Platforming

I want to know more about Cross-Platform. I'm currently working on my thesis and decided to make an Android Application but not all target users uses Android device. So, We've come up with an idea to Cross-Platform the android application.
I have read the same topic but it didn't get to me too well. iOS / Android cross platform development. I want to know if there is another way than using the frameworks discussed in the link.
I want know what is the best/shortest way to cross platform a Android Application?

Cross Platform tools are in my opinion not a good idea at all. Android is Java, and iOS is Objective C. Android can use NDK to use a C/C++ library so theoretically if you did most of your code in C/C+ it could be used on both sides. I think two natives is more in order. Study NDK to see what could run on both devices. Lets say you built your app as a C++ Library except for UI interactions. Then in theory the library should work on both sides. C/C++ a lot easier on iOS than android however.
Also it really depends on the dependencies your app will have. Lets say you want to use a library but its only available in Java or C++ how does this effect your decision.
You might also consider designing your app so that it just captures data on the devices and the actual processing of the data takes place in a web service.

Another way is use Mobile Web HTML5 Framework like Phonegapp, Sencha touch and more.
Although web technologies don’t perform as well as native, but it is a useful thing that you can try.
See Choosing Mobile Web HTML5 Framework and http://operationproject.com/2011/adventures-in-html5-part-one/

Android application are apk files that are basically zip file that contains dex/odex files and all other resources that you may wish to add.But I think you can use any coding language to develop as long as you have IDE that converts your code to apk and dex .And most important of all your programming language must support corresponding api or must have something similar to cross compile.The reason Google used Java for Android was they felt it is convenient to do it(read it during case Google v/s Oracle)
Personally I feel cross-platform is good since it increases the developers base and understanding of the System (here Android).And I think the same analogy would go with other Systems as well.

Building Peer to Peer photo sharing on Android

I am planning to do a project on Peer to Peer photo sharing on Android. My professor wants me to do that using some language other than Java or C/C++. Is any of Erlang, Haskell, Ocaml,
Scala, Go helpful to build an android app with following functionality?
Ability to design a GUI for android to view the pictures to be shared
Support for socket communications to transfer the pictures?

Since Android relies heavily on Java, Scala would be a good choice here. Scala makes interoperating with Java code easy and runs on the JVM. On top of this, it is a nice functional language with an interesting type system, so it will be a good learning experience. (So will your other languages, but Scala is probably easier to use on Android.)
Check out Scala Programming for Android, which describes how you can make Android applications in Scala.

You can compile and execute Go programs on Android (or ARM in general), but you can't actually use the Android libraries. So, writing services or GUI applications for Android in Go is currently not that easy. I am not sure about the other languages, but I think Erlang, Haskell, Ocaml, etc. have similar problems (if they even provide an ARM compiler).
Therefore it's probably best to focus on a JVM based language. Most of the examples and other applications are written in Java, but Scala is also able to access all those APIs. So, I would either use Java or Scala.

There's also this JVM-based functional, dynamic, lisp-like language Clojure, which some people seem to like a lot. It should be possible to use it to write Android Apps.

Well, in my view, it depends on what you want to really use the language for as regards your project. Photo Sharing: are you planning on using Web based tools for the client, i.e. JavaScript, HTML5, CSS3, JQuery Mobile (http://jquerymobile.com/), sencha Touch (http://www.sencha.com/products/touch), Phone Gap (http://phonegap.com/),Titanium Appcelerator OR you want to use native stuff like Java, J2ME, e.t.c. Then if its web based (which would make things easier in my view), the language you are referring to in this case would be on the Server side. So in my view if you just need the language to web-serve photos and stuff, then it would not matter which one you use: really depends on your liking. I am pretty sure that Erlang, Scala, Java and the others all have capability for developing great web services. However, the conditions you put as below:
1) Ability to design a GUI for android to view the pictures to be shared 2) Support for socket communications to transfer the pictures?
Suggest that you were referring to a Front-End technology to use. You cannot use Erlang to create GUIs on Android, if i am right, you may not also be able to use Haskell and OcamL as well because these technologies cannot run on the device. For GUIs on Android, you can only use Java, OR you can use Widget Technologies like Opera Widgets OR you use Web based stuff like i mentioned above. However, you should know that using JavaScript Libraries, HTML5, CSS3, e.t.c. is the quickest and more manageable way of developing Apps on any Device. I even wonder why you are talking of Socket Communications !! Am i getting you right ? you want to develop a Photo Sharing App which transfers Photos over raw Socket Communications ? Well, i am NOT sure how many apps out there for Android are doing raw Socket stuff, but i am pretty sure that many (http://androidapplications.com/) are using HTTP Protocol, as in Web Services. Consider looking into web services than raw Sockets. I am pretty sure that even apps developed using native Java, uses HTTP (Web Services like SOAP) to communicate with a remote Server, be it weather apps, location-based stuff e.t.c. Otherwise i guess you should concentrate on Java, for now.