调用需要 API 级别 21（当前最小值为 19）：android.view.View()

Question

So I want to create a library that use custom view. I want to inherit View class, but it's error because my minsdk is 19. I need my library to support sdk 19. Is there a way to solve this?

class Dummy() :  View(context, attrs, defStyleAttr, defStyleRes) {

Answer 1

You should use another constructor for this. The one you used is available only from the API 21.

For custom views I use it like this:

class Dummy @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0)
: View(context, attrs, defStyleAttr)

So 2 things here:

1. Use View constructor with 3 params. Context, attrs, defStyleAttr.
2. Use @JvmOverloads annotation and default values for parameters to support actually 3 constructors in one line.