new cleaner approach of not whacking services seems to aprox work

app/src/main/aidl/com/geeksville/mesh/IMeshService.aidl

@@ -58,6 +58,7 @@ interface IMeshService {
     String connectionState();
 
     /// If a macaddress we will try to talk to our device, if null we will be idle.
+    /// Any current connection will be dropped (even if the device address is the same) before reconnecting.
     /// Users should not call this directly, only used internally by the MeshUtil activity
     void setDeviceAddress(String deviceAddr);
 

app/src/main/aidl/com/geeksville/mesh/IRadioInterfaceService.aidl

@@ -23,6 +23,7 @@ interface IRadioInterfaceService {
     void writeOwner(in byte [] owner);
 
     /// If a macaddress we will try to talk to our device, if null we will be idle.
+    /// Any current connection will be dropped (even if the device address is the same) before reconnecting.
     /// Users should not call this directly, called only by MeshService
     void setDeviceAddress(String deviceAddr);
 }

app/src/main/java/com/geeksville/mesh/MainActivity.kt

@@ -118,7 +118,7 @@ class MainActivity : AppCompatActivity(), Logging,
         bluetoothManager.adapter
     }
 
-    private val model: UIViewModel by viewModels()
+    val model: UIViewModel by viewModels()
 
     data class TabInfo(val text: String, val icon: Int, val content: Fragment)
 
@@ -176,7 +176,7 @@ class MainActivity : AppCompatActivity(), Logging,
             Manifest.permission.BLUETOOTH,
             Manifest.permission.BLUETOOTH_ADMIN,
             Manifest.permission.WAKE_LOCK
-            
+
             // We only need this for logging to capture files for the simulator - turn off for most users
             // Manifest.permission.WRITE_EXTERNAL_STORAGE
         )

app/src/main/java/com/geeksville/mesh/service/MeshService.kt

@@ -479,14 +479,14 @@ class MeshService : Service(), Logging {
     private fun loadSettings() {
         try {
             getPrefs().getString("json", null)?.let { asString ->
+                discardNodeDB() // Get rid of any old state 
+                
                 val json = Json(JsonConfiguration.Default)
                 val settings = json.parse(SavedSettings.serializer(), asString)
                 myNodeInfo = settings.myInfo
 
                 // put our node array into our two different map representations
-                nodeDBbyNodeNum.clear()
                 nodeDBbyNodeNum.putAll(settings.nodeDB.map { Pair(it.num, it) })
-                nodeDBbyID.clear()
                 nodeDBbyID.putAll(settings.nodeDB.mapNotNull {
                     it.user?.let { user -> // ignore records that don't have a valid user
                         Pair(
@@ -497,7 +497,6 @@ class MeshService : Service(), Logging {
                 })
                 // Note: we do not haveNodeDB = true because that means we've got a valid db from a real device (rather than this possibly stale hint)
 
-                recentDataPackets.clear()
                 recentDataPackets.addAll(settings.messages)
             }
         } catch (ex: Exception) {
@@ -505,6 +504,17 @@ class MeshService : Service(), Logging {
         }
     }
 
+    /**
+     * discard entire node db & message state - used when changing radio channels
+     */
+    private fun discardNodeDB() {
+        myNodeInfo = null
+        nodeDBbyNodeNum.clear()
+        nodeDBbyID.clear()
+        recentDataPackets.clear()
+        haveNodeDB = false
+    }
+
     var myNodeInfo: MyNodeInfo? = null
 
     private var radioConfig: MeshProtos.RadioConfig? = null
@@ -1067,6 +1077,7 @@ class MeshService : Service(), Logging {
 
         override fun setDeviceAddress(deviceAddr: String?) {
             debug("Passing through device change to radio service: $deviceAddr")
+            discardNodeDB()
             connectedRadio.setDeviceAddress(deviceAddr)
         }
 

app/src/main/java/com/geeksville/mesh/ui/SettingsFragment.kt

@@ -36,9 +36,9 @@ object SLogging : Logging {}
 
 /// Change to a new macaddr selection, updating GUI and radio
 fun changeDeviceSelection(context: MainActivity, newAddr: String?) {
-    model.meshService?.let { service ->
-        service.setDeviceAddress(context, newAddr)
-
+    // FIXME, this is a kinda yucky way to find the service
+    context.model.meshService?.let { service ->
+        service.setDeviceAddress(newAddr)
     }
 }
 
@@ -317,8 +317,6 @@ class SettingsFragment : ScreenFragment("Settings"), Logging {
                     reportError("Clicked Report A Bug")
                 }
                 .show()
-
-            true
         }
     }