Kotlin Extension Functions Databinding

Question

Is there any possibility to use extension function with a databinding? XML:

Answer 1

While @skiff2011 is correct, one could also use alias to prevent the Kt postfix.

For example, a certain extension function is located in ExtensionFunctionsKt can be aliased by ExtensionFunctions

<import
    alias="ExtensionFunctions"
    type="com.helloworld.app.util.ExtensionFunctionsKt" />

<variable
    name="someData"
    type="com.helloworld.app.model.SomeData" />

The ExtensionFunction alias can now be used to call the extension function. The first argument still needs to be the extended class variable.

<TextView
    android:id="@+id/city"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@{ExtensionFunctions.doStuff(someData)}" />

Answer 2

You have to import CityKt firstly into xml

<import type="my.package.domain.country.model.CityKt" />

int the data section then you can use it like this

<TextView
  android:id="@+id/city"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="@{CityKt.streetName(city)}" />

If you review CityKt you will see that there is static Java method with City as first argument

Answer 3

If using Utils class you can to this:

 object Utils(){
       fun streetName(): String {}
}

<import
    type="com.helloworld.app.util.Utils" />



  <TextView
                android:id="@+id/txt" 
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@{Utils.INSTANCE.streetName()}"
              />