initial setup with UI & package structure

app/src/main/java/com/example/refactoredapp/presentation/MainActivity.kt

@@ -0,0 +1,49 @@
+package com.example.refactoredapp.presentation
+
+import android.os.Bundle
+import android.view.View
+import android.widget.AdapterView
+import android.widget.ArrayAdapter
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.ViewModelProvider
+import com.example.refactoredapp.R
+import com.example.refactoredapp.databinding.ActivityMainBinding
+
+class MainActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityMainBinding
+    private lateinit var viewModel: MainViewModel
+
+    private val TAG = "MainActivity"
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+        viewModel = ViewModelProvider(this)[MainViewModel::class.java]
+        setDropDownMenu()
+    }
+
+    private fun setDropDownMenu() {
+        val adapter = ArrayAdapter.createFromResource(
+            this,
+            R.array.instrument, android.R.layout.simple_spinner_item
+        )
+        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
+        binding.spinnerDevice.adapter = adapter
+        binding.spinnerDevice.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
+            override fun onItemSelected(
+                parent: AdapterView<*>,
+                p1: View?,
+                position: Int,
+                p3: Long
+            ) {
+                viewModel.device = parent.getItemAtPosition(position).toString()
+            }
+
+            override fun onNothingSelected(p0: AdapterView<*>?) {}
+        }
+    }
+
+
+}

app/src/main/java/com/example/refactoredapp/presentation/MainViewModel.kt

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+package com.example.refactoredapp.presentation
+
+import androidx.lifecycle.ViewModel
+
+class MainViewModel : ViewModel() {
+
+    var device = ""
+}