Use the method of onlayoutchangelistener to solve the problem of gettop = 0

 private val mLayoutChangeListener: View.OnLayoutChangeListener by lazy {
        View.OnLayoutChangeListener { _, _, _, _, _, _, _, _, _ ->
            checkPosition()
            mLayout.postDelayed({
            	// Contact monitoring 
                mLayoutt.removeOnLayoutChangeListener(mLayoutChangeListener)
            }, 500)
        }
    }

override fun initView(rootView: View) {
	// Add listening 
	mLayout.addOnLayoutChangeListener(mLayoutChangeListener)
}

private fun checkPosition(){
        val aViewY = mAView.top
        val bViewtY = mBView.top + mBView.measuredHeight
    }