ViewModel

1. create new class for extend viewModel()

    class MainActivityViewModel: ViewModel() {
   
        var count = 0
        fun addNumber() {
            count++
        }
    }
   

2. initialisasi object ViewModel in onCreate()

    /**
     * inisialisasi object ViewModel
     */
    val viewModelMain = ViewModelProvider(this).get(MainActivityViewModel::class.java)
   

3. finally get onject viewModel

      /**
       * agar bila dirotet tidak bermasalah maka
       * textView_Number.text = viewModelMain.count.toString()
       * dilektakan kembali di onCreate
       */
      textView_Number.text = viewModelMain.count.toString()
   
      button_Count_It.setOnClickListener {
          viewModelMain.addNumber()
          textView_Number.text = viewModelMain.count.toString()
      }
   

   }