Develop Reference

Kotlin classes with underscores

Please explain me what is the purpose and meaning of classes like StringsKt__StringsKt (i.e. doubled class name with one or more underscores in between) and, similarly, StringsKt__StringsJVMKt?
Strings are not the only example, there are many others too. I see them when looking into the structure of the classes.dex file in my .apk.
screenshot here
I'm asking because I faced a situation where I had to explicitly state some of them in my proguard-rules. The app crashed without it.

It is a generated file. A file like that will be generated if there are several Kotlin files named with same JvmName.
Let's take Strings.kt and StringNumberConversions.kt as an example:
// StringNumberConversions.kt
#file:kotlin.jvm.JvmMultifileClass
#file:kotlin.jvm.JvmName("StringsKt")
...
// Strings.kt
#file:kotlin.jvm.JvmMultifileClass
#file:kotlin.jvm.JvmName("StringsKt")
...
Both of them have #file:kotlin.jvm.JvmName("StringsKt"), so StringsKt and StringsKt__StringNumberConversionsKt are generated to distinguish them.

Xamarin Binding Android JAR - duplicate partial class

I'm trying to create a binding project for OpenTok.jar so I can use version 2.7 with Xamarin. My binding project is unable to build because it generates two of the same classes. SubscriberKit.DisconnectedEventArgs exists two times which I cannot seem to Transform away.
Anyone have a solution for this or tried anything like this?
The access to the solution can be found here:
https://ebbits.tnmconsult.dk:9445/downloads/agrinord.apk
The error I receive is: "Severity Code Description Project File Line Suppression State
Error CS0111 Type 'SubscriberKit.DisconnectedEventArgs' already defines a member called '.ctor' with the same parameter types OpenTokBinding'"

If got help from Xamarin and the answer was to look at the parent of the classes (the once which references them).
The proberty was found in SubscriberKit.SubscriberListener and SubscriberKit.StreamListener both had a method/ event called onDisconnect which lead to two DisconnectedEventArgs classes. So once I renamed these two event to:
- SubscriberOnDisconnected
- StreamOnDisconnected
It worked. Code for renaming was placed in Metadata.xml and looked like:
<attr path="/api/package[#name='com.opentok.android']/interface[#name='SubscriberKit.SubscriberListener']/method[#name='onDisconnected']" name="managedName">SubscriberOnDisconnected</attr>
<attr path="/api/package[#name='com.opentok.android']/interface[#name='SubscriberKit.StreamListener']/method[#name='onDisconnected']" name="managedName">StreamOnDisconnected</attr>

How to add the global keyword to Metadata.xml for Xamarin jar binding?

I am attempting to bind a jar file to a Xamarin bindings project. For a particular field, the global keyword needs to be used in order to avoid ambiguity between 2 namespaces (com.paypal.android & android.widget).
Error CS0234: The type or namespace name 'Widget' does not exist in the namespace 'Com.Paypal.Android'. Are you missing an assembly reference?
Xamarin is smart enough to include the global keywords within the field's getter and setter; unfortunately, Xamarin isn't smart enough to to include it in the field's type:
public IList<Android.Widget.TextView> C {
When I alter the code itself, it gets overwritten when I rebuild the project. I believe I need to add the global keyword inside the Metadata.xml (although, I'm not quite sure how).
I've attempted to add the following in order to change the return type:
<attr path="/api/package[#name='com.paypal.android.sdk']/class[#name='cD']/field[#name='c']" name="managedReturn"> NOT SURE WHAT GOES HERE </attr>

Binding for AndTinder library

I am trying to create a binding library for android AndTinder library. But I am getting the following error
Error CS0507: 'Com.Andtinder.View.SimpleCardStackAdapter.GetCardView(int, Com.Andtinder.Model.CardModel, Android.Views.View, Android.Views.ViewGroup)': cannot change access modifiers when overriding 'protected' inherited member 'Com.Andtinder.View.CardStackAdapter.GetCardView(int, Com.Andtinder.Model.CardModel, Android.Views.View, Android.Views.ViewGroup)' (CS0507)
To fix the above error , I added the following line to Metadata.xml
<attr path="/api/package[#name='Com.AndTinder.View']/class[#name='CardStackAdapter']/method[#name='GetCardView']" name="visibility">protected</attr>
But this has not fixed. I would appreciate if someone could give me hints on how to fix this error

The base class is protected. So you want to fix this by changing the C# version to protected as well.
Based on the package: package com.andtinder.view;
And the MethodName getCardView: https://github.com/kikoso/Swipeable-Cards/blob/master/AndTinder/src/main/java/com/andtinder/view/CardStackAdapter.java#L69
<attr path="/api/package[#name='com.andtinder.view']/class[#name='CardStackAdapter']/method[#name='getCardView']" name="visibility">protected</attr>
Overall it seems like you just need to ensure your case sensitivity and this should work!

Porting Card.IO to C# Xamarin Studio

I'm having trouble trying to port Card.IO to Xamarin Android. Since I am using C# instead of Java, I don't know what to do with the .so files and the .jar files.
I tried to follow some of the steps posted here : card.io Mono for Android (Xamarin Studio) but I am getting the following two build errors that I don't know how to solve.
Here's What I've done so far
Create a new Android Java Bindings Library Project
Add the .jar and .so files from Card.IO project, with the existing folder structure. So there is four subfolders under the /libs folder, and then a single jar under /libs.
Add the following to Transforms/EnumMethods.xml to resolve a compiler error:
<mapping jni-class="io/card/payment/CardIOActivity">
<method jni-name="onActivityResult" parameter="p1" clr-enum-type="Android.App.Result" />
</mapping>
Add a reference to the above Library in my main application.
And then I am faced with these build errors :
The type or namespace name 'IN' does not exist in the namespace
'IO.Card.Payment' (are you missing an assembly reference?)
'A': member names cannot be the same as their enclosing type
Update
The first error is on this line :
public sealed partial class CardIOActivity : global::Android.App.Activity, global::IO.Card.Payment.IN {
The second error seems to be on this line :
public static global::System.Collections.IList A {
Any help is useful, thanks!

i've spent like 10 hours yday to get card io working with my xamarin application... after long long battles i managed to see what i wanted... i did not see the above error about 2 interfaces, i've had an issue with 'a' field in 'A' class and there as an error telling that "IN" interface does not exist (this is an interface, so no problem with double base class should be shown there, that's odd).
not sure if all my steps are necessary to make it working but (surprise, surprise) i was to tired to clean that up and check which chagnes were really essencial. lots of problems are cause by the code obfuscation of the card io jar.
nevermind, back to the topic:
create new binding project, add the jar as embeded jar, add the .so files as embided native libraries (use the existing structure)
open EnumMethods.xml and add there a mapping:
<mapping jni-class="io/card/payment/CardIOActivity">
<method jni-name="onActivityResult" parameter="p1" clr-enum-type="Android.App.Result" />
</mapping>
(this changes int to enum type used by .net xamarin in the onActivityResult method (which is overloaded by one of the classes in card.io.jar)
3. open Metadata.xml and add below nodes (some might be unnecessary):
<attr path="/api/package[#name='io.card.payment']/class[#name='A']/field[#name='a']" name="managedName">AProp</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='M']" name="visibility">public</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='M']" name="name">Mcl</attr>
<attr path="/api/package[#name='io.card.payment']/interface[#name='N']" name="visibility">public</attr>
<attr path="/api/package[#name='io.card.payment']/interface[#name='N']" name="name">Nifc</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='L']" name="visibility">public</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='L']/field[#name='a']" name="managedName">aProp</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='L']/method[#name='a']" name="managedName">aMethod</attr>
<attr path="/api/package[#name='io.card.payment']/class[#name='L']" name="name">Lcl</attr>
above nodes change some visibilities to public (most needed) and change some names of classes or iterfaces (not sure if needed, but it was useful to me at some point)
add reference to the binding project in the main one.
open AndroidManifest.xml in the main project and add there:
<activity android:name="io.card.payment.CardIOActivity" android:configChanges="keyboardHidden|orientation" />
<activity android:name="io.card.payment.DataEntryActivity" android:screenOrientation="portrait"/>
nodes should be added under application node (which is a child of main node - manifest)
now you should be able to invoke the CardIOActivity and use what you want (invoking and using is available and seems to be described well in the examples provided by the creators)
one more hint, nothing big, but when i finally succeeded in getting the library working i missed it... to get result as CreditResult object in OnActivityResult method use java cast:
var scanResult = data.GetParcelableExtra(CardIOActivity.ExtraScanResult).JavaCast();
ordinary c# cast won't work.
if you have any problems let me know, perhaps i missed something (especially that i'm not yet xamarin expert).
good luck!
ps: answer placed #xamarin forum too
EDIT:
Completet solution with binding, checked and working uploded to github:
https://github.com/wiadran/card.io.xamarin.binding.git