Using alternative constructors for fragments to avoid NPE

app/src/main/java/com/rtbishop/look4sat/ui/AboutFragment.kt

@@ -21,37 +21,19 @@ package com.rtbishop.look4sat.ui
 
 import android.os.Bundle
 import android.text.method.LinkMovementMethod
-import android.view.LayoutInflater
 import android.view.View
-import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import com.rtbishop.look4sat.BuildConfig
 import com.rtbishop.look4sat.R
 import com.rtbishop.look4sat.databinding.FragmentAboutBinding
 
-class AboutFragment : Fragment() {
-
-    private var _binding: FragmentAboutBinding? = null
-    private val binding get() = _binding!!
-
-    override fun onCreateView(
-        inflater: LayoutInflater,
-        container: ViewGroup?,
-        savedInstanceState: Bundle?
-    ): View? {
-        _binding = FragmentAboutBinding.inflate(inflater, container, false)
-        return binding.root
-    }
+class AboutFragment : Fragment(R.layout.fragment_about) {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
+        val binding = FragmentAboutBinding.bind(view)
         binding.tvAboutVersion.text =
             String.format(getString(R.string.app_version), BuildConfig.VERSION_NAME)
         binding.tvAboutMessage.movementMethod = LinkMovementMethod.getInstance()
     }
-
-    override fun onDestroyView() {
-        _binding = null
-        super.onDestroyView()
-    }
 }

app/src/main/java/com/rtbishop/look4sat/ui/MapViewFragment.kt

@@ -22,9 +22,7 @@ package com.rtbishop.look4sat.ui
 import android.content.Context
 import android.graphics.*
 import android.os.Bundle
-import android.view.LayoutInflater
 import android.view.View
-import android.view.ViewGroup
 import android.widget.Toast
 import androidx.appcompat.app.AlertDialog
 import androidx.core.content.ContextCompat
@@ -41,16 +39,11 @@ import com.rtbishop.look4sat.predict4kotlin.PassPredictor
 import com.rtbishop.look4sat.repo.SatPass
 import java.util.*
 import java.util.concurrent.Executors
-import java.util.concurrent.ScheduledExecutorService
 import java.util.concurrent.TimeUnit
 import kotlin.math.abs
 
-class MapViewFragment : Fragment() {
+class MapViewFragment : Fragment(R.layout.fragment_map_view) {
 
-    private var _binding: FragmentMapViewBinding? = null
-    private val binding get() = _binding!!
-
-    private lateinit var service: ScheduledExecutorService
     private lateinit var mainActivity: MainActivity
     private lateinit var viewModel: MainViewModel
     private lateinit var mapView: MapView
@@ -60,29 +53,12 @@ class MapViewFragment : Fragment() {
     private lateinit var satPassList: List<SatPass>
     private var checkedItem = 0
 
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        service = Executors.newSingleThreadScheduledExecutor()
-        mainActivity = activity as MainActivity
-        viewModel = ViewModelProvider(mainActivity).get(MainViewModel::class.java)
-    }
-
-    override fun onCreateView(
-        inflater: LayoutInflater,
-        container: ViewGroup?,
-        savedInstanceState: Bundle?
-    ): View? {
-        _binding = FragmentMapViewBinding.inflate(layoutInflater, container, false)
-        return binding.root
-    }
-
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        setupComponents()
-    }
-
-    private fun setupComponents() {
-        val refreshRate = viewModel.getRefreshRate()
+        val binding = FragmentMapViewBinding.bind(view)
+        val service = Executors.newSingleThreadScheduledExecutor()
+        mainActivity = activity as MainActivity
+        viewModel = ViewModelProvider(mainActivity).get(MainViewModel::class.java)
         gsp = viewModel.getGSP().value ?: GroundStationPosition(0.0, 0.0, 0.0)
         satPassList = viewModel.getSatPassList().value ?: emptyList()
 
@@ -92,12 +68,12 @@ class MapViewFragment : Fragment() {
             binding.fabMap.setOnClickListener { showSelectSatDialog(satPassList) }
             selectedSat = satPassList.first().tle
             predictor = satPassList.first().predictor
-            mapView = MapView(mainActivity)
+            mapView = MapView(mainActivity, binding)
             binding.frameMap.addView(mapView)
             service.scheduleAtFixedRate(
                 { mapView.invalidate() },
-                refreshRate,
-                refreshRate,
+                viewModel.getRefreshRate(),
+                viewModel.getRefreshRate(),
                 TimeUnit.MILLISECONDS
             )
         } else {
@@ -131,7 +107,8 @@ class MapViewFragment : Fragment() {
             .show()
     }
 
-    inner class MapView(context: Context) : View(context) {
+    inner class MapView(context: Context, private val binding: FragmentMapViewBinding) :
+        View(context) {
         private val scale = resources.displayMetrics.density
         private val groundTrackPaint = Paint().apply {
             isAntiAlias = true
@@ -318,9 +295,4 @@ class MapViewFragment : Fragment() {
             return value * 180 / Math.PI
         }
     }
-
-    override fun onDestroyView() {
-        _binding = null
-        super.onDestroyView()
-    }
 }

app/src/main/java/com/rtbishop/look4sat/ui/PassListFragment.kt

@@ -53,17 +53,13 @@ class PassListFragment : Fragment(R.layout.fragment_pass_list) {
     private lateinit var satPassList: MutableList<SatPass>
     private var isTimerSet: Boolean = false
 
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+        val fragmentBinding = FragmentPassListBinding.bind(view)
         mainActivity = activity as MainActivity
         viewModel = ViewModelProvider(mainActivity).get(MainViewModel::class.java)
         satPassAdapter = SatPassAdapter(viewModel)
         satPassList = mutableListOf()
-    }
-
-    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        super.onViewCreated(view, savedInstanceState)
-        val fragmentBinding = FragmentPassListBinding.bind(view)
         aosTimerText = mainActivity.findViewById(R.id.toolbar_timer)
         btnPassPrefs = mainActivity.findViewById(R.id.toolbar_filter)
         setupComponents(fragmentBinding)

app/src/main/java/com/rtbishop/look4sat/ui/PolarViewFragment.kt

@@ -24,9 +24,7 @@ import android.graphics.Canvas
 import android.graphics.Paint
 import android.graphics.Path
 import android.os.Bundle
-import android.view.LayoutInflater
 import android.view.View
-import android.view.ViewGroup
 import androidx.core.content.ContextCompat
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.ViewModelProvider
@@ -46,44 +44,28 @@ import java.util.concurrent.TimeUnit
 import kotlin.math.cos
 import kotlin.math.sin
 
-class PolarViewFragment : Fragment() {
+class PolarViewFragment : Fragment(R.layout.fragment_polar_view) {
 
     private val service = Executors.newSingleThreadScheduledExecutor()
     private val args: PolarViewFragmentArgs by navArgs()
 
-    private var _binding: FragmentPolarViewBinding? = null
-    private val binding get() = _binding!!
-
     private lateinit var viewModel: MainViewModel
     private lateinit var satPass: SatPass
     private lateinit var polarView: PolarView
     private lateinit var transmitterAdapter: TransmitterAdapter
     private lateinit var mainActivity: MainActivity
 
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        mainActivity = activity as MainActivity
-        viewModel = ViewModelProvider(mainActivity).get(MainViewModel::class.java)
-    }
-
-    override fun onCreateView(
-        inflater: LayoutInflater,
-        container: ViewGroup?,
-        savedInstanceState: Bundle?
-    ): View? {
-        _binding = FragmentPolarViewBinding.inflate(layoutInflater, container, false)
-        return binding.root
-    }
-
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-
+        val binding = FragmentPolarViewBinding.bind(view)
+        mainActivity = activity as MainActivity
+        viewModel = ViewModelProvider(mainActivity).get(MainViewModel::class.java)
         viewModel.getSatPassList().value?.let {
             val refreshRate = viewModel.getRefreshRate()
             satPass = it[args.satPassIndex]
             mainActivity.supportActionBar?.title = satPass.tle.name
 
-            polarView = PolarView(mainActivity, refreshRate)
+            polarView = PolarView(mainActivity, refreshRate, binding)
             binding.framePolar.addView(polarView)
             service.scheduleAtFixedRate(
                 { polarView.invalidate() },
@@ -92,11 +74,11 @@ class PolarViewFragment : Fragment() {
                 TimeUnit.MILLISECONDS
             )
 
-            setupTransRecycler()
+            setupTransRecycler(binding)
         }
     }
 
-    private fun setupTransRecycler() {
+    private fun setupTransRecycler(binding: FragmentPolarViewBinding) {
         transmitterAdapter = TransmitterAdapter()
         binding.recPolar.apply {
             layoutManager = LinearLayoutManager(mainActivity)
@@ -114,7 +96,12 @@ class PolarViewFragment : Fragment() {
         }
     }
 
-    inner class PolarView(context: Context, updateFreq: Long) : View(context) {
+    inner class PolarView(
+        context: Context,
+        private val updateFreq: Long,
+        private val binding: FragmentPolarViewBinding
+    ) :
+        View(context) {
 
         private val radarSize = resources.displayMetrics.widthPixels
         private val scale = resources.displayMetrics.density
@@ -124,7 +111,6 @@ class PolarViewFragment : Fragment() {
         private val piDiv2 = Math.PI / 2.0
         private val txtSize = scale * 15
         private val center = 0f
-        private val delay = updateFreq
 
         private val radarPaint = Paint().apply {
             isAntiAlias = true
@@ -223,7 +209,7 @@ class PolarViewFragment : Fragment() {
                 } else {
                     path.lineTo(satPassX, satPassY)
                 }
-                startTime.time += delay
+                startTime.time += updateFreq
             }
             cvs.drawPath(path, trackPaint)
         }
@@ -253,9 +239,4 @@ class PolarViewFragment : Fragment() {
             return value * 180 / Math.PI
         }
     }
-
-    override fun onDestroyView() {
-        _binding = null
-        super.onDestroyView()
-    }
 }

app/src/main/java/com/rtbishop/look4sat/ui/SatEntryDialog.kt

@@ -36,15 +36,12 @@ class SatEntryDialog : AppCompatDialogFragment(), SearchView.OnQueryTextListener
     private lateinit var satEntryAdapter: SatEntryAdapter
     private lateinit var entriesListener: EntriesSubmitListener
 
-    private var _binding: DialogSatEntryBinding? = null
-    private val binding get() = _binding!!
-
     private var entriesList = mutableListOf<SatEntry>()
     private var selectionList = mutableListOf<Int>()
     private var selectAllToggle = true
 
     override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
-        _binding = DialogSatEntryBinding.inflate(requireActivity().layoutInflater)
+        val binding = DialogSatEntryBinding.inflate(requireActivity().layoutInflater)
         val satEntryDialog = Dialog(requireActivity()).apply {
             window?.requestFeature(Window.FEATURE_NO_TITLE)
             setContentView(binding.root)
@@ -147,9 +144,4 @@ class SatEntryDialog : AppCompatDialogFragment(), SearchView.OnQueryTextListener
     interface EntriesSubmitListener {
         fun onEntriesSubmit(list: MutableList<Int>)
     }
-
-    override fun onDestroyView() {
-        _binding = null
-        super.onDestroyView()
-    }
 }