Mit app Inventor WiFi Extension code not working but not showing error

Open Source Development Extension Development
,
1 
package in.sam;

import android.app.Activity;

import android.content.Context;

import com.google.appinventor.components.annotations.*;

import com.google.appinventor.components.common.ComponentCategory;

import com.google.appinventor.components.runtime.AndroidNonvisibleComponent;

import com.google.appinventor.components.runtime.ComponentContainer;

import com.google.appinventor.components.runtime.EventDispatcher;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.net.wifi.ScanResult;

import android.net.wifi.WifiConfiguration;

import android.net.wifi.WifiManager;

import com.google.appinventor.components.annotations.*;

import com.google.appinventor.components.common.ComponentCategory;

import com.google.appinventor.components.runtime.*;

import com.google.appinventor.components.runtime.util.YailList;

import java.util.ArrayList;

import java.util.List;

@DesignerComponent(

        version = 1,

        description = "",

        category = ComponentCategory.EXTENSION,

        nonVisible = true,

        iconName = "")

@SimpleObject(external = true)

//Libraries

@UsesLibraries(libraries = "")

//Permissions

@UsesPermissions(permissionNames = "android.permission.ACCESS_NETWORK_STATE,android.permission.ACCESS_WIFI_STATE,android.permission.CHANGE_WIFI_STATE")

public class CrystalWiFi extends AndroidNonvisibleComponent {

    //Activity and Context

    private Context context;

    private Activity activity;

    private WifiManager wifiManager;

    private BroadcastReceiver wifiScanReceiver;

    public CrystalWiFi(ComponentContainer container){

        super(container.$form());

        this.activity = container.$context();

        this.context = container.$context();

        this.wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);

        wifiScanReceiver = new BroadcastReceiver() {

            @Override

            public void onReceive(Context context, Intent intent) {

                if (WifiManager.SCAN_RESULTS_AVAILABLE_ACTION.equals(intent.getAction())) {

                    List<String> availableNetworks = new ArrayList<>();

                    for (ScanResult result : wifiManager.getScanResults()) {

                        availableNetworks.add(result.SSID);

                    }

                    YailList networkList = YailList.makeList(availableNetworks);

                    onNetworksListReceived(networkList);

                }

            }

        };

        context.registerReceiver(wifiScanReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));        

    }

     @SimpleFunction(description = "Scan for available WiFi networks.")

    public void ScanNetwork() {

        wifiManager.startScan();

    }

    @SimpleEvent(description = "Fired when the Wi-Fi scan is completed.")

    public void onNetworksListReceived(YailList networkList) {

        EventDispatcher.dispatchEvent(this, "onNetworksListReceived", networkList);

    }

    @SimpleFunction(description = "Connect to a WiFi network with SSID and password.")

    public void ConnectToNetwork(String ssid, String password) {

        WifiConfiguration wifiConfig = new WifiConfiguration();

        wifiConfig.SSID = "\"" + ssid + "\"";

        wifiConfig.preSharedKey = "\"" + password + "\"";

        int netId = wifiManager.addNetwork(wifiConfig);

        wifiManager.disconnect();

        wifiManager.enableNetwork(netId, true);

        wifiManager.reconnect();

    }

    @SimpleFunction(description = "Disconnect from the currently connected WiFi network.")

    public void Disconnect() {

        wifiManager.disconnect();
    }
}
2

To scan for available networks you need location permission and GPS must be enabled
Also the startScan method has been deprecated in SDK28, see here WifiManager  |  Android Developers

You can find a working wifi extension here

Google changed a lot in the last SDK updates and everything around wifi is not so easy anymore, especially connecting to a ssid...

Taifun

3 
package in.sam;

import android.app.Activity;

import android.content.Context;

import android.util.Log; // Add this import statement

import com.google.appinventor.components.annotations.*;

import com.google.appinventor.components.common.ComponentCategory;

import com.google.appinventor.components.runtime.AndroidNonvisibleComponent;

import com.google.appinventor.components.runtime.ComponentContainer;

import com.google.appinventor.components.runtime.EventDispatcher;

import android.content.BroadcastReceiver;

import android.content.Intent;

import android.content.IntentFilter;

import android.net.wifi.ScanResult;

import android.net.wifi.WifiConfiguration;

import android.net.wifi.WifiManager;

import com.google.appinventor.components.annotations.*;

import com.google.appinventor.components.common.ComponentCategory;

import com.google.appinventor.components.runtime.*;

import com.google.appinventor.components.runtime.util.YailList;

import java.util.ArrayList;

import java.util.List;

@DesignerComponent(

        version = 1,

        description = "",

        category = ComponentCategory.EXTENSION,

        nonVisible = true,

        iconName = "")

@SimpleObject(external = true)

// Libraries

@UsesLibraries(libraries = "")

// Permissions

@UsesPermissions(permissionNames = "android.permission.ACCESS_NETWORK_STATE,android.permission.ACCESS_WIFI_STATE,android.permission.CHANGE_WIFI_STATE,android.permission.ACCESS_FINE_LOCATION,android.permission.ACCESS_COARSE_LOCATION")

public class CrystalWiFi extends AndroidNonvisibleComponent {

    // Activity and Context

    private Context context;

    private Activity activity;

    private WifiManager wifiManager;

    private BroadcastReceiver wifiScanReceiver;

    public CrystalWiFi(ComponentContainer container) {

        super(container.$form());

        this.activity = container.$context();

        this.context = container.$context();

        this.wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);

        wifiScanReceiver = new BroadcastReceiver() {

            @Override

            public void onReceive(Context context, Intent intent) {

                try {

                    if (WifiManager.SCAN_RESULTS_AVAILABLE_ACTION.equals(intent.getAction())) {

                        List<String> availableNetworks = new ArrayList<>();

                        for (ScanResult result : wifiManager.getScanResults()) {

                            availableNetworks.add(result.SSID);

                        }

                        YailList networkList = YailList.makeList(availableNetworks);

                        onNetworksListReceived(networkList);

                    }

                } catch (Exception e) {

                    Log.e("CrystalWiFi", "Error in onReceive: " + e.getMessage());

                }

            }

        };

        context.registerReceiver(wifiScanReceiver, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

    }

    @SimpleFunction(description = "Scan for available WiFi networks.")

    public void ScanNetwork() {

        try {

            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.P) {

                wifiManager.startScan();

            } else {

                wifiManager.startScan();

            }

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in ScanNetwork: " + e.getMessage());

        }

    }

    @SimpleEvent(description = "Fired when the Wi-Fi scan is completed.")

    public void onNetworksListReceived(YailList networkList) {

        try {

            EventDispatcher.dispatchEvent(this, "onNetworksListReceived", networkList);

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in onNetworksListReceived: " + e.getMessage());

        }

    }

    @SimpleFunction(description = "Connect to a WiFi network with SSID and password.")

    public void ConnectToNetwork(String ssid, String password) {

        try {

            WifiConfiguration wifiConfig = new WifiConfiguration();

            wifiConfig.SSID = "\"" + ssid + "\"";

            wifiConfig.preSharedKey = "\"" + password + "\"";

            int netId = wifiManager.addNetwork(wifiConfig);

            wifiManager.disconnect();

            wifiManager.enableNetwork(netId, true);

            wifiManager.reconnect();

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in ConnectToNetwork: " + e.getMessage());

        }

    }

    @SimpleFunction(description = "Disconnect from the currently connected WiFi network.")

    public void Disconnect() {

        try {

            wifiManager.disconnect();

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in Disconnect: " + e.getMessage());

        }

    }

    @SimpleFunction(description = "Enable WiFi.")

    public void EnableWiFi() {

        try {

            wifiManager.setWifiEnabled(true);

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in EnableWiFi: " + e.getMessage());

        }

    }

    @SimpleFunction(description = "Disable WiFi.")

    public void DisableWiFi() {

        try {

            wifiManager.setWifiEnabled(false);

        } catch (Exception e) {

            Log.e("CrystalWiFi", "Error in DisableWiFi: " + e.getMessage());

        }

    }

}

Hi
I added GPS Permission
Still Problem Persist

4

This is not only to add permissions in the manifest, you also have to ask for the permissions

Create a test project and use logcat to see what is going on

Taifun