From java:
onView(withId(R.id.recyclerView)).perform(RecyclerViewActions.scrollTo(
hasDescendant(withText(artistResult.getNameVariations().get(0)))));
Trying to convert to Kotlin:
onView(withId(R.id.recyclerView)).perform(RecyclerViewActions.scrollTo(
hasDescendant(withText(artistResult.nameVariations[0]))))
I get this stacktrace:
Error:(63, 71) Type inference failed: Not enough information to infer parameter VH in fun <VH : RecyclerView.ViewHolder!> scrollTo(itemViewMatcher: Matcher<View!>!): RecyclerViewActions.PositionableRecyclerViewAction!
Please specify it explicitly.
I'm not entirely sure where I can specify "it" explicitly. When this has come up previously it's because I didn't initialise the value correctly, but here I'm calling a method. Any ideas?
I needed to add <RecyclerView.ViewHolder> to scrollTo
onView(withId(R.id.recyclerView)).perform(
RecyclerViewActions.scrollTo<RecyclerView.ViewHolder>(
hasDescendant(withText(artistResult.nameVariations[0]))))
One can get easily confused about which VH among many(specially if multiple VHs in a single RecyclerView) to use, you can simply use Generic ViewHolder i.e RecyclerView.ViewHolder like :
RecyclerViewActions.actionOnItem<RecyclerView.ViewHolder>
RecyclerViewActions.actionOnHolderItem<RecyclerView.ViewHolder>
RecyclerViewActions.actionOnItemAtPosition<RecyclerView.ViewHolder>
etc.
I hope this helps.
I´m just going to leave my solution here in case anyone needs it.
onView(withId(androidx.preference.R.id.recycler_view))
.perform(actionOnItem<RecyclerView.ViewHolder>(hasDescendant(withText(R.string.settings_reset_app)), click()).atPosition(1));
do this:
onView(withId(R.id.recycler_view))
.perform(RecyclerViewActions.scrollToPosition(11))
Related
Google turns up nothing on this error: Combination of indirect name lookup and call not supported
My code:
use Vimwiki::File::TextProcessingClasses;
unit class Vimwiki::File::ContentStr;
has Str $.content;
method process($class) {
$!content = Vimwiki::File::TextProcessingClasses::($class).process($!content);
}
The compiler is not happy with this and complains with aforesaid error. If I hard-code in in the $class name, everything works.
Anyway around this?
OK, solution is to precede the package name with ::, like so:
$!content = ::Vimwiki::File::TextProcessingClasses::($class).process($!content);
Documentation is here: https://docs.raku.org/language/packages#Looking_up_names
Though I don't know precisely why what I was doing originally behaves differently.
What do the brackets mean before a function?
For example:
TextView myTextView = (TextView)findViewById(R.id.tvHello);
Here the (TextView) part is what I have problem with. Is it something like a parameter for
fun <T> findViewByID(...) {...}
First, some history. findViewById used to simply return View, even if the type of the found view was more specific, such as a TextView. So if you wanted to find a view and assign it to a variable with a specific type of View, you would have to cast it to that variable type.
Casting doesn't change the underlying object. It just tells the compiler that you promise that the underlying object already is that more specific type, so the compiler will let you treat it like the more specific type and assign it to a variable of that more specific type.
Your first block of code is Java. The class name in parentheses casts the following expression to a specific class. In Kotlin, you cast by using as, so it would look like:
myTextView: TextView = findViewById(R.id.tvHello) as TextView
However, in later versions of Android and in the support libraries, they changed findViewById to return a generic type T that extends View. This allows Java and Kotlin to implicitly cast the result to the type of the variable you assign the result to. So now you can just use
myTextView: TextView = findViewById(R.id.tvHello)
and it will automatically cast to TextView for you.
When you see code like your first block of code, it probably originated from old code from before the change to findViewById.
Generics are a pretty big topic, and the Kotlin documentation on it is written as if you're already highly familiar with Java generics. So I recommend reading the Java docs on it first, even if you don't really know Java. The explanation will still help you understand what generics do.
It's a cast.
That converts the result of findViewByID to TextView.
Note that with the latest kotlin API that isn't needed. findViewByID has a type parameter T and will automatically return an object of the view type you like.
Once, when that code was written, findViewByID was returning a plain View and callers had to cast it to the desired type.
In this case those brackets that contain (TextView) before the function are used to specify what kind of this you should get when you are done executing the function.
If there is a possible ambiguity about the type of thing you get when you are done executing the function, you do what is called a cast. In this case we cast the returned result to (TextView).
To understand the most basic case of casting I suggest you look at how long/double/float cast in C and Java.
I'm trying to create two almost-same methods that handle nullable and non-nullable arguments slightly differently:
fun parse(type: Any) : MyObject {
return handleParse(type)
}
fun parse(type: Any?) : MyObject? {
if (type == null)
return null
return handleParse(type)
}
But I get this error in Android Studio:
Platform declaration clash: The following declarations have the same JVM signature
The goal is that it automatically handles nullable and non-nullable values in Kotlin, without me using !! every time I call it on nullable terms.
I've already tried adding the #JvmName("-name") annotation as mentioned in this answer but that doesn't work either. Obviously, I can change the method name to something else as well, but that is just circling around and avoiding the issue altogether.
Hoping there's an easy way to do this or at least a sensible workaround. Would also appreciate the reasoning behind the way things currently work, and why I should or shouldn't do this.
Reason why this doesn't work is simple, Java doesn't have null-safe types, meaning that both methods look completely same to Java, and Kotlin aims to provide as much interoperability with Java as possible.
But if you think a bit more about that there is simply no reason for such feature, as you can see your 2nd method already handles everything properly, with addition of 1 if case, which even if this feature exist would have to exist because compiler would need to know whether value in null or not in other to know which method to call anyway.
Common approach that I have seen so far is adding NotNull suffix to your method, for example in your case it would be parseNotNull in case where you don't allow nullable types, this way even when calling code from Java it is clear that parameter shouldn't be null.
I am trying to form below final kotlin code
val participants: List<AbstractParty>
I tried to use below code in kotlinpoet but it shows error, I think it is not correct, but don't know how should I fix it. Any one can help? Thanks.
PropertySpec.builder("participants", List<ClassName("AbstractParty">)
Depending on whether you have a reference to a class or if you need to create its name from Strings, you can do either this:
PropertySpec.builder("participants",
ParameterizedTypeName.get(List::class, AbstractParty::class)
).build()
Or this:
PropertySpec.builder("participants",
ParameterizedTypeName.get(
List::class.asClassName(),
ClassName("some.pckg.name", "AbstractParty"))
).build()
A hint to finding out these sorts of things: KotlinPoet has pretty extensive tests, you can find examples of almost anything in there.
You can use parameterizedBy() extension:
PropertySpec.builder(
"participants",
List::class.asClassName().parameterizedBy(ClassName("some.pckg.name", "AbstractParty")
).build()
https://square.github.io/kotlinpoet/1.x/kotlinpoet/kotlinpoet/com.squareup.kotlinpoet/-parameterized-type-name/-companion/parameterized-by.html
As you seen in this picture below, for some reason my DirectCast wont except ANYTHING for the second argument. It says it requires a type, but, it won't take any object at all!
Thanks for any help! I'm using VB.net so all .net answers are acceptable :)
EDIT
Ok, so apparently I'm not giving it the right kind of type. Could somebody please clarify this? Assuming the type it needs to cast to is gridElement, what should I replace objType with?
DirectCast requires an object prototype (i.e. just giving it the intended class name) rather than a System.Type descriptor object. To cast an object using a System.Type, you will want to utilize CTypeDynamic():
Return CTypeDynamic(createElementByIdAndLayer.MemberwiseClone(), objType)
The error is essentially telling you a class with the type name "objType" does not exist.
Its expecting a "Type", not a "Type Object".
What is the return value of the function?