我想自定义 Kotlin 中的新按钮时遇到问题

Question

I have this error in my code when I create myButton in Kotlin.

Answer 1

Button is a Function, not a class extended. Just make an function in MainActivity

For example

    class MainActivity : AppCompatActivity(){
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        MyButton()  // this is how to make button inside function

    }

    private fun MyButton(){

     // you can put your button listener here
     // example :

     mMyBtn.setOnClickListener {
            // and then put ur logic here
            Toast.makeText(this, "Button Clicked", Toast.LENGTH_SHORT).show()
        }

    }
}

or maybe try below

class MyButton : androidx.appcompat.widget.AppCompatButton {
    constructor(context: Context?) : super(context!!)
    constructor(context: Context?, attrs: AttributeSet?) : super(context!!, attrs)
    constructor(context: Context?, attrs: AttributeSet?, defStyle: Int) : super(context!!, attrs, defStyle)

    protected override fun onDraw(canvasObject: Canvas) {
        super.onDraw(canvasObject)
    }
}

let me know if this works for you:)

Answer 2

Firstly it a warning, not an error. Your code will still run fine. But the reason for this warning/suggestion is because AppCompatButton is part of androidx library also comes with backward support for some features, they are also tint aware meaning it allows dynamic and background tints.

From the documentation of AppCompatButton

A Button which supports compatible features on older versions of the platform, >including:

• Allows dynamic tint of its background via the background tint methods in ViewCompat.
• Allows setting of the background tint using R.attr.backgroundTint and R.attr.backgroundTintMode.
• Allows setting of the font family using R.attr.fontFamily.
• This will automatically be used when you use Button in your layouts and the top-level activity / dialog is provided by appcompat. You should only need to manually use this class when writing custom views.

From above, When ever you use a Button , it automatically uses AppCompatButton , so you should take care of extending AppCompatButton in custom views to get most of it.