无法添加窗口——令牌 null 无效

Question

我得到 无法添加窗口——令牌 null 无效 错误在 onStartCommand() 方法行：

windowManager.addView(overlayView, params)

class OverlayService : Service() {
    private lateinit var windowManager: WindowManager
    private lateinit var overlayView: View

    override fun onBind(intent: Intent?): IBinder? {
        TODO("Not yet implemented")
    }

    override fun onCreate() {
        windowManager = getSystemService(WINDOW_SERVICE) as WindowManager
        overlayView = View(this)
        
        super.onCreate()
    }

    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {

        val params = WindowManager.LayoutParams()

        windowManager.addView(overlayView, params)

        return super.onStartCommand(intent, flags, startId)
    }


    override fun onDestroy() {
        super.onDestroy()
        windowManager.removeView(overlayView)
    }


    private fun getRunningAppPackageName(): String {
        return  "some package name"
    }

}