Tell about your experience creating and using custom user interface components in Android.

In Android, I created custom user interface components by extending standard View or ViewGroup. For example, I implemented a custom progress indicator with animation, which inherited from View and overridden the onDraw and onMeasure methods for custom drawing and sizing.

Example:

class CustomProgressView(context: Context, attrs: AttributeSet) : View(context, attrs) {
    private val paint = Paint().apply { color = Color.BLUE; strokeWidth = 10f }
    private var progress = 0

    override fun onDraw(canvas: Canvas) {
        super.onDraw(canvas)
        val width = width * progress / 100
        canvas.drawRect(0f, 0f, width.toFloat(), height.toFloat(), paint)
    }

    fun setProgress(value: Int) {
        progress = value.coerceIn(0, 100)
        invalidate()
    }
}

This approach allows creating unique interface elements that are difficult or impossible to implement with standard tools.