A WiFi Manager

Hello there. I'm a university student on Computer Science from Greece and the last few months I want to teach myself how to develop applications for Android. I bought 2 books (Android Application Development for Dummies, Pro Android 2) which have been really helpful so far for creating very small apps and widgets. But I want to challenge my self to something more difficult. I had this idea of creating a WiFi manager in my spare time, only to find out that creating such an app is more difficult than expected, at least for my programming skills. But that won't hold my horses. It is widely known that if you want to learn how to code, you have to read code, then write a little, then read again, then write some more etc. And that's what I'm about to do.

I was surprised to find out that the available coding samples on WiFi for Android on the net are scarce. The only code sample easy to understand for dummies like me is this. So I begun to read carefully each line, understand it and then coping it to my demo application named WiFire. (Yeah, I know...) Yet, the application does not work both on Eclipse and my HTC Desire. I get the message: "The application WiFire has stopped unexpectedly. Please try again." So the first thing I want to find out is why the app doesn't work? I suspect that it has something to do with the version of Android because this code sample is from November 2009. I guess a lot of things have changed since then.

At this point I want to make some things clear. I really hope that coping this code doesn't violate any of the rules of the forum. As you can see in the link, it's a code sample so I guess it exists to learn from that (which means coping and modify it). My goal isn't coping code. My goal is to learn. So I don't care how many weeks/months will this going to take. I want to make a WiFi Manager in order to learn deep Android developing. So, I will post every few days/weeks new parts of code which I'll have written and with your constructive comments I will improve my skills. For the record, if I make it (and that's a big if), I'm planning to make this app open sourced.

But first things first! I need to understand the code. Below is the WiFire main Activity file:

package icsd.mittos.wifire;


import java.util.List;

import android.app.Activity;

import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.IntentFilter;

import android.net.wifi.WifiConfiguration;

import android.net.wifi.WifiInfo;

import android.net.wifi.WifiManager;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

import android.widget.Toast;


public class WiFireActivity extends Activity {

	

	private static final String TAG = "WiFire";

	WifiManager wifi;

    BroadcastReceiver receiver;

    

    TextView textStatus;

	Button buttonScan;

	

    /** Called when the activity is first created. */

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.main);

        

        // Setup UI

     	textStatus = (TextView) findViewById(R.id.textStatus);

     	buttonScan = (Button) findViewById(R.id.buttonScan);

     	buttonScan.setOnClickListener((OnClickListener) this);

        

     	// Setup WiFi

        wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);

        

        // Get WiFi status

        WifiInfo info = wifi.getConnectionInfo();

        textStatus.append("\n\nWiFi Status: " + info.toString());

        

        // List available networks

        List<WifiConfiguration> configs = wifi.getConfiguredNetworks();

        for (WifiConfiguration config : configs) {

        	textStatus.append("\n\n" + config.toString());

        }

        

        // Register Broadcast Receiver

        if (receiver == null)

        	receiver = new WiFiScanReceiver(this);

        

        registerReceiver(receiver, new IntentFilter(

				WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));

		Log.d(TAG, "onCreate()");

	}


	@Override

	public void onStop() {

		unregisterReceiver(receiver);

	}


	public void onClick(View view) {

		Toast.makeText(this, "On Click Clicked. Toast to that!!!",

				Toast.LENGTH_LONG).show();


		if (view.getId() == R.id.buttonScan) {

			Log.d(TAG, "onClick() wifi.startScan()");

			wifi.startScan();

		}

	}

}

Below is the ScanReceiver file:

package icsd.mittos.wifire;


import java.util.List;


import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.net.wifi.ScanResult;

import android.net.wifi.WifiManager;

import android.util.Log;

import android.widget.Toast;


public class WiFiScanReceiver extends BroadcastReceiver {

	

	private static final String TAG = "WiFiScanReceiver";

	WiFireActivity wifire;

	

	public WiFiScanReceiver(WiFireActivity wifire) {

		super();

		this.wifire = wifire;

	}


	@Override

	public void onReceive(Context context, Intent intent) {

		List<ScanResult> results = wifire.wifi.getScanResults();

		ScanResult bestSignal = null;

		for (ScanResult result : results) {

			if (bestSignal == null || WifiManager.compareSignalLevel(bestSignal.level, result.level) < 0)

				bestSignal = result;

		}

		

		String message = String.format("%s networks found. %s is the strongest.", results.size(), bestSignal.SSID);

		Toast.makeText(wifire, message, Toast.LENGTH_LONG).show();

		

		Log.d(TAG, "onReceive() message: " + message);

	}


}

This is the XML:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

  android:orientation="vertical" android:layout_width="fill_parent"

  android:layout_height="fill_parent">


  <Button android:layout_width="wrap_content"

    android:layout_height="wrap_content" android:id="@+id/buttonScan"

    android:text="Scan"></Button>

  <ScrollView android:id="@+id/ScrollView01"

    android:layout_width="wrap_content" android:layout_height="wrap_content">

    <TextView android:layout_width="fill_parent"

      android:layout_height="wrap_content" android:id="@+id/textStatus"

      android:text="WiFiDemo" />

  </ScrollView>

</LinearLayout>

And this is the Manifest:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="icsd.mittos.wifire"

    android:versionCode="1"

    android:versionName="1.0" >


    <uses-sdk android:minSdkVersion="10" />

    

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

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


    <application

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name" >

        <activity

            android:label="@string/app_name"

            android:name=".WiFireActivity" >

            <intent-filter >

                <action android:name="android.intent.action.MAIN" />


                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>


</manifest>

The 4 files above are exactly the same as the ones here, the only difference is the name of the app. Also I have created my own XML as a mockup for the app I want to create in due time:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent"

    android:orientation="vertical" >


    <LinearLayout

        android:id="@+id/linearLayout1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:padding="5dp" >


        <Button

            android:id="@+id/AutoScan"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"

            android:layout_weight="50"

            android:text="AutoScan" />


        <Button

            android:id="@+id/Refresh"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"

            android:layout_weight="50"

            android:text="Refresh" />

    </LinearLayout>


    <RelativeLayout

        android:id="@+id/InformationRelativeLayout"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content" >


        <TextView

            android:id="@+id/Signal"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_alignParentRight="true"

            android:layout_alignParentTop="true"

            android:layout_marginRight="10dp"

            android:text="Signal" />


        <TextView

            android:id="@+id/SSID"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_alignParentLeft="true"

            android:layout_alignParentTop="true"

            android:layout_marginLeft="10dp"

            android:text="SSID" />


    </RelativeLayout>


    <LinearLayout

        android:id="@+id/linearLayout4"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:orientation="vertical" >

        

        <TableLayout xmlns:android="http://schemas.android.com/apk/res/android"

    		android:layout_width="fill_parent"

    		android:layout_height="fill_parent"

    		android:stretchColumns="1">

    		

    		<TableRow>

    		    

       		 	<TextView

            		android:text="Grand Line" 

            		android:layout_marginLeft="10dp" 

            		android:layout_weight="50" 

            		android:layout_width="fill_parent"/>

       		 	

        		<TextView

            		android:text="99%"

            		android:gravity="right"

            		android:padding="3dip" 

            		android:layout_width="fill_parent" 

            		android:layout_weight="50" 

            		android:layout_marginRight="10dp"/>

        		

    		</TableRow>

    		

		</TableLayout>

        

        

    </LinearLayout>

  

    <RelativeLayout 

        android:id="@+id/InnerRelativeLayout"

        android:layout_width="fill_parent"

        android:layout_height="fill_parent"

        android:padding="5dp" >

       

		<LinearLayout

      		android:id="@+id/linearLayout2"

      	  	android:layout_width="match_parent"

      	  	android:layout_height="wrap_content"

      	  	android:layout_alignParentBottom="true" >

      	  	

		 <Button

            android:id="@+id/ManagerButton"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Manager" 

            android:layout_weight="33.3"

            android:layout_alignParentBottom="true"/>


        <Button

            android:id="@+id/RadarButton"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Radar" 

            android:layout_weight="33.3"

            android:layout_alignParentBottom="true"/>


        <Button

            android:id="@+id/MapButton"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Map" 

            android:layout_weight="33.3"

            android:layout_alignParentBottom="true"/>

      	  	

		</LinearLayout>

    

    </RelativeLayout>


</LinearLayout>

But that's useless right now.

So my first question is: What am I missing? Why the app doesn't work?

Thanks in advance, I hope this will be a pleasant journey. :)