Set static IP and gateway programmatically in Android 6.x (Marshmallow)

Since there's no official API I have to come up with a solution by modifying samples from the following code snipet and this answer. This solution works on devices from Lollipop upwards.

 @SuppressWarnings("unchecked")
 public static void setStaticIpConfiguration(WifiManager manager, WifiConfiguration config, InetAddress ipAddress, int prefixLength, InetAddress gateway, InetAddress[] dns) throws ClassNotFoundException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException, NoSuchFieldException, InstantiationException {
        // First set up IpAssignment to STATIC.
        Object ipAssignment = getEnumValue("android.net.IpConfiguration$IpAssignment", "STATIC");
        callMethod(config, "setIpAssignment", new String[]{"android.net.IpConfiguration$IpAssignment"}, new Object[]{ipAssignment});

        // Then set properties in StaticIpConfiguration.
        Object staticIpConfig = newInstance("android.net.StaticIpConfiguration");
        Object linkAddress = newInstance("android.net.LinkAddress", new Class<?>[]{InetAddress.class, int.class}, new Object[]{ipAddress, prefixLength});

        setField(staticIpConfig, "ipAddress", linkAddress);
        setField(staticIpConfig, "gateway", gateway);
        getField(staticIpConfig, "dnsServers", ArrayList.class).clear();
        for (int i = 0; i < dns.length; i++)
            getField(staticIpConfig, "dnsServers", ArrayList.class).add(dns[i]);

        callMethod(config, "setStaticIpConfiguration", new String[]{"android.net.StaticIpConfiguration"}, new Object[]{staticIpConfig});

        int netId = manager.updateNetwork(config);
        boolean result = netId != -1;
        if (result) {
            boolean isDisconnected = manager.disconnect();
            boolean configSaved = manager.saveConfiguration();
            boolean isEnabled = manager.enableNetwork(config.networkId, true);
            boolean isReconnected = manager.reconnect();
        }
    }

Helper functions,

    public static WifiConfiguration getCurrentWiFiConfiguration(Context context) {
            WifiConfiguration wifiConf = null;
            ConnectivityManager connManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
            if (networkInfo.isConnected()) {
                final WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
                final WifiInfo connectionInfo = wifiManager.getConnectionInfo();
                if (connectionInfo != null && !TextUtils.isEmpty(connectionInfo.getSSID())) {
                    List<WifiConfiguration> configuredNetworks = wifiManager.getConfiguredNetworks();
                    if (configuredNetworks != null) {
                        for (WifiConfiguration conf : configuredNetworks) {
                            if (conf.networkId == connectionInfo.getNetworkId()) {
                                wifiConf = conf;
                                break;
                            }
                        }
                    }
                }
            }
            return wifiConf;
        }

 private static Object newInstance(String className) throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException, IllegalArgumentException, InvocationTargetException {
        return newInstance(className, new Class<?>[0], new Object[0]);
    }

    private static Object newInstance(String className, Class<?>[] parameterClasses, Object[] parameterValues) throws NoSuchMethodException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, ClassNotFoundException {
        Class<?> clz = Class.forName(className);
        Constructor<?> constructor = clz.getConstructor(parameterClasses);
        return constructor.newInstance(parameterValues);
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static Object getEnumValue(String enumClassName, String enumValue) throws ClassNotFoundException {
        Class<Enum> enumClz = (Class<Enum>) Class.forName(enumClassName);
        return Enum.valueOf(enumClz, enumValue);
    }

    private static void setField(Object object, String fieldName, Object value) throws IllegalAccessException, IllegalArgumentException, NoSuchFieldException {
        Field field = object.getClass().getDeclaredField(fieldName);
        field.set(object, value);
    }

    private static <T> T getField(Object object, String fieldName, Class<T> type) throws IllegalAccessException, IllegalArgumentException, NoSuchFieldException {
        Field field = object.getClass().getDeclaredField(fieldName);
        return type.cast(field.get(object));
    }

    private static void callMethod(Object object, String methodName, String[] parameterTypes, Object[] parameterValues) throws ClassNotFoundException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException {
        Class<?>[] parameterClasses = new Class<?>[parameterTypes.length];
        for (int i = 0; i < parameterTypes.length; i++)
            parameterClasses[i] = Class.forName(parameterTypes[i]);

        Method method = object.getClass().getDeclaredMethod(methodName, parameterClasses);
        method.invoke(object, parameterValues);
    }

To use it,

WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
WifiConfiguration wifiConf = WifiHelper.getCurrentWiFiConfiguration(getApplicationContext());

        try {
            setStaticIpConfiguration(wifiManager, wifiConf,
                    InetAddress.getByName("192.168.0.100"),
                    24,
                    InetAddress.getByName("10.0.0.2"),
                    new InetAddress[]{InetAddress.getByName("10.0.0.3"), InetAddress.getByName("10.0.0.4")});

        } catch (Exception e) {
            e.printStackTrace();
        }

Finally you need to add those permissions in the manifest,

  <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
  <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
  <uses-permission android:name="android.permission.WRITE_SETTINGS" />

I've dug some into the problem and my findings is that code that used to work for Andrdoi 5.x might work if the application is set to be the device owner.

Solution:

The solution is to add the device as deviceOwner. This will allow for static IP to be set using the 5.x hacks as referenced by Mogi. A good example of how this is done is using the example found here:

https://github.com/googlesamples/android-DeviceOwner/

Using adb shell and running the command:

dpm set-device-owner com.example.android.deviceowner/.DeviceOwnerReceiver

will make it ready to be allowed to do its job.