Error when try to start local Hotspot on android part of a flutter app

Question

I've got a flutter app in which I want to start the hotspot of the device. So I have to write some platform specific code on android to use hotspot.

I got this that compiles without a problem:

try {
            if (call.method == "startLocalOnlyHotspot")  {
                var wifiManager: WifiManager = applicationContext.getSystemService(Context.WIFI_SERVICE) as WifiManager
                
                wifiManager.startLocalOnlyHotspot(object : WifiManager.LocalOnlyHotspotCallback() {
                    override fun onStarted(localOnlyHotspotReservation: WifiManager.LocalOnlyHotspotReservation) {
                        super.onStarted(localOnlyHotspotReservation)
                        result.success(localOnlyHotspotReservation)
                    }

                    override fun onStopped() {
                        super.onStopped()
                        result.success(null)
                    }

                    override fun onFailed(reason: Int) {
                        super.onFailed(reason)
                        result.success(null)
                    }
                }, Handler())
                // log the results
                Log.d("Hotspot", "Hotspot started")
                // result.success(ApManager.configApState(this)) 
            } else {
                result.notImplemented()
            }
        } catch (e: Exception) {
            result.error("ERROR", e.message, null)
        }

But when I call this code from flutter with this:

await platform.invokeMethod('startLocalOnlyHotspot');

the app crashes with I think this main error:

java.lang.IllegalArgumentException: Unsupported value: 'android.net.wifi.WifiManager$LocalOnlyHotspotReservation@f603f75' of type 'class android.net.wifi.WifiManager$LocalOnlyHotspotReservation'

But if it's not that, I put the full error stack here :

W/WifiManager(28567): com.kwikwink.kw_delivery attempted call to setWifiApEnabled: enabled = false D/Hotspot (28567): Hotspot started D/WifiManager(28567): LocalOnlyHotspotCallbackProxy: handle message what: 0 msg: { when=0 what=0 obj=* ID: -2 SSID: AndroidShare_2246 PROVIDER-NAME: null BSSID: null FQDN: null PRIO: 0 HIDDEN: false PMF: false D/WifiManager(28567): NetworkSelectionStatus NETWORK_SELECTION_ENABLED D/WifiManager(28567): hasEverConnected: false D/WifiManager(28567): KeyMgmt: WPA2_PSK Protocols: D/WifiManager(28567): AuthAlgorithms: D/WifiManager(28567): PairwiseCiphers: D/WifiManager(28567): GroupCiphers: D/WifiManager(28567): PSK: * D/WifiManager(28567): Enterprise config: D/WifiManager(28567): eap NULL D/WifiManager(28567): phase2 "auth=NULL" D/WifiManager(28567): IP config: D/WifiManager(28567): IP assignment: UNASSIGNED D/WifiManager(28567): Proxy settings: UNASSIGNED D/WifiManager(28567): cuid=-1 luid=-1 lcuid=0 userApproved=USER_UNSPECIFIED noInternetAccessExpected=false D/WifiManager(28567): recentFailure: Association Rejection code: 0 D/WifiManager(28567): D/WifiManager(28567): samsungSpecificFlags: D/WifiManager(28567): semAutoWifiScore: 0 D/WifiManager(28567): isVendorAp : false D/WifiManager(28567): recoverableRSSI: -200 D/WifiManager(28567): inRecoverArea: false D/WifiManager(28567): disabledTime: 0 D/WifiManager(28567): notInRangeTime: 0 D/WifiManager(28567): isUsableInternet: false D/WifiManager(28567): skipInternetCheck: -1 D/WifiManager(28567): notAskAgainCheck: false D/WifiManager(28567): nextTargetRssi: 0 D/WifiManager(28567): isCaptivePortal: false D/WifiManager(28567): isAuthenticated: false D/WifiManager(28567): loginUrl: null D/WifiManager(28567): autoReconnect: 1 D/WifiManager(28567): isRecommended: false D/WifiManager(28567): isHomeProviderNetwork: false D/WifiManager(28567): WapiCertIndex: 0 D/WifiManager(28567): WapiPskType: 0 D/WifiManager(28567): isWeChatAp : false D/WifiManager(28567): entryRssi24GHz : -78 D/WifiManager(28567): entryRssi5GHz : -75 target=android.net.wifi.WifiManager$LocalOnlyHotspotCallbackProxy$1 } D/AndroidRuntime(28567): Shutting down VM E/AndroidRuntime(28567): FATAL EXCEPTION: main E/AndroidRuntime(28567): Process: com.kwikwink.kw_delivery, PID: 28567 E/AndroidRuntime(28567): java.lang.IllegalArgumentException: Unsupported value: 'android.net.wifi.WifiManager$LocalOnlyHotspotReservation@f603f75' of type 'class android.net.wifi.WifiManager$LocalOnlyHotspotReservation' E/AndroidRuntime(28567): at io.flutter.plugin.common.StandardMessageCodec.writeValue(StandardMessageCodec.java:297) E/AndroidRuntime(28567): at io.flutter.plugin.common.StandardMethodCodec.encodeSuccessEnvelope(StandardMethodCodec.java:63) E/AndroidRuntime(28567): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler$1.success(MethodChannel.java:267) E/AndroidRuntime(28567): at com.kwikwink.kw_delivery.MainActivity$configureFlutterEngine$1$1.onStarted(MainActivity.kt:33) E/AndroidRuntime(28567): at android.net.wifi.WifiManager$LocalOnlyHotspotCallbackProxy$1.handleMessage(WifiManager.java:3755) E/AndroidRuntime(28567): at android.os.Handler.dispatchMessage(Handler.java:106) E/AndroidRuntime(28567): at android.os.Looper.loop(Looper.java:214) E/AndroidRuntime(28567): at android.app.ActivityThread.main(ActivityThread.java:7050) E/AndroidRuntime(28567): at java.lang.reflect.Method.invoke(Native Method) E/AndroidRuntime(28567): at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494) E/AndroidRuntime(28567): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:965) I/Process (28567): Sending signal. PID: 28567 SIG: 9 Lost connection to device.

If anyone can help me with this it could be lovely. Thanks anyway!

score 0 · Accepted Answer · answered Oct 26 '22 at 18:18

0

The problem is in this line:

  result.success(localOnlyHotspotReservation)

You cannot return a Java object (in this case WifiManager$LocalOnlyHotspotReservation) from a method call - just supported values (integers, strings, lists, maps, etc).

If you'd like to return some particular value from there, like the SSID, you'd need to extract it in the native code and return that (supported) type. For example:

  result.success(localOnlyHotspotReservation.getSoftApConfiguration().getWifiSsid().toString())

answered Oct 26 '22 at 18:18

Richard Heap

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I try your solution but it didn't work but I don't have the same error now. I wrote this code to return the ssid and passphrase : `var hotSpotSuccess = localOnlyHotspotReservation.getSoftApConfiguration().getWifiSsid().toString() + "|" + localOnlyHotspotReservation.getSoftApConfiguration().getPassphrase() result.success(hotSpotSuccess)` but i got this error : `java.lang.NoSuchMethodError: No virtual method getSoftApConfiguration()Landroid/net/wifi/SoftApConfiguration;` – un_cafeinoman Oct 27 '22 at 07:49
1

Probably means your phone isn't on API 30 - try using `getWifiConfiguration` instead. That's an Android issue, rather than a Flutter method channel issue. Now that you know how to return values from Flutter native method calls, you could return a fixed string for now for testing and ask an Android only question about how to handle the API 30 issue. – Richard Heap Oct 27 '22 at 14:36
I will try to do that though. your help have been huge thanks a lot ! – un_cafeinoman Oct 28 '22 at 08:57
You were right it surly was an issue with the api lvl, the method `getWifiConfiguration` work perfectly fine – un_cafeinoman Oct 28 '22 at 09:56

Error when try to start local Hotspot on android part of a flutter app

1 Answers1