How can I get Android Wifi Scan Results into a list?

Try this code

public class WiFiDemo extends Activity implements OnClickListener
 {      
    WifiManager wifi;       
    ListView lv;
    TextView textStatus;
    Button buttonScan;
    int size = 0;
    List<ScanResult> results;

    String ITEM_KEY = "key";
    ArrayList<HashMap<String, String>> arraylist = new ArrayList<HashMap<String, String>>();
    SimpleAdapter adapter;

    /* Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        textStatus = (TextView) findViewById(R.id.textStatus);
        buttonScan = (Button) findViewById(R.id.buttonScan);
        buttonScan.setOnClickListener(this);
        lv = (ListView)findViewById(R.id.list);

        wifi = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
        if (wifi.isWifiEnabled() == false)
        {
            Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled", Toast.LENGTH_LONG).show();
            wifi.setWifiEnabled(true);
        }   
        this.adapter = new SimpleAdapter(WiFiDemo.this, arraylist, R.layout.row, new String[] { ITEM_KEY }, new int[] { R.id.list_value });
        lv.setAdapter(this.adapter);

        registerReceiver(new BroadcastReceiver()
        {
            @Override
            public void onReceive(Context c, Intent intent) 
            {
               results = wifi.getScanResults();
               size = results.size();
            }
        }, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));                    
    }

    public void onClick(View view) 
    {
        arraylist.clear();          
        wifi.startScan();

        Toast.makeText(this, "Scanning...." + size, Toast.LENGTH_SHORT).show();
        try 
        {
            size = size - 1;
            while (size >= 0) 
            {   
                HashMap<String, String> item = new HashMap<String, String>();                       
                item.put(ITEM_KEY, results.get(size).SSID + "  " + results.get(size).capabilities);

                arraylist.add(item);
                size--;
                adapter.notifyDataSetChanged();                 
            } 
        }
        catch (Exception e)
        { }         
    }    
}

WiFiDemo.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="16dp"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/textStatus"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="Status" />

        <Button
            android:id="@+id/buttonScan"
            android:layout_width="wrap_content"
            android:layout_height="40dp"
            android:text="Scan" />
    </LinearLayout>

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="20dp"></ListView>
</LinearLayout>

For ListView- row.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:padding="8dp">

    <TextView
        android:id="@+id/list_value"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="14dp" />
</LinearLayout>

Add these permission in AndroidManifest.xml

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

Wrap an ArrayAdapter around your List<ScanResult>. Override getView() to populate your rows with the ScanResult data. Here is a free excerpt from one of my books that covers how to create custom ArrayAdapters like this.

In addition for the accepted answer you'll need the following permissions into your AndroidManifest to get it working:

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