Kotlin hierarchy: Storing child class in parent var-CodePudding

Having a parent class named Shading, which is abstract and a child class named GradientShading, in java it was so easy to store a child object into a variable of the parent type:

Shading act=null;
act=new GradienShading();

In kotlin I don't know how to do it, because this gives compilation error:

lateinit var act: Shading
act = GradienShading()

Type mismatch. Required: Shading Found: GradienShading

Can anyone help me with this easy thing in kotlin?

Thanks

CodePudding user response：

Presumably you've not set up the type hierarchy correctly. Are you sure Shading in fact is a supertype of GradientShading? The following compiles just fine on my machine.

open class Shading
class GradientShading: Shading()

class Example {
    lateinit var act: Shading
    
    fun test() {
        act = GradientShading()
    }
}