ClientScanResult.java

public class ClientScanResult {
private String IpAddr;

private String HWAddr;

private String Device;

private boolean isReachable;

public ClientScanResult(String ipAddr, String hWAddr, String device, boolean isReachable) {
    super();
    IpAddr = ipAddr;
    HWAddr = hWAddr;
    Device = device;
    this.setReachable(isReachable);
}

public String getIpAddr() {
    return IpAddr;
}

public void setIpAddr(String ipAddr) {
    IpAddr = ipAddr;
}

public String getHWAddr() {
    return HWAddr;
}

public void setHWAddr(String hWAddr) {
    HWAddr = hWAddr;
}

public String getDevice() {
    return Device;
}

public void setDevice(String device) {
    Device = device;
}

public void setReachable(boolean isReachable) {
    this.isReachable = isReachable;
}

public boolean isReachable() {
    return isReachable;
}

@Override
public String toString() {
    return "ClientScanResult{" +
            "IpAddr='" + IpAddr + '\'' +
            ", HWAddr='" + HWAddr + '\'' +
            ", Device='" + Device + '\'' +
            ", isReachable=" + isReachable +
            '}';
}
}

WifiApManager.java

 public class WifiApManager {
 private final WifiManager mWifiManager;

public WifiApManager(Context context) {
    mWifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
}


/**
 * Gets a list of the clients connected to the Hotspot, reachable timeout is 300
 *
 * @param onlyReachables {@code false} if the list should contain unreachable (probably disconnected) clients, {@code true} otherwise
 * @return ArrayList of {@link ClientScanResult}
 */
public ArrayList<ClientScanResult> getClientList(boolean onlyReachables) {
    return getClientList(onlyReachables, 300);
}

/**
 * Gets a list of the clients connected to the Hotspot
 *
 * @param onlyReachables   {@code false} if the list should contain unreachable (probably disconnected) clients, {@code true} otherwise
 * @param reachableTimeout Reachable Timout in miliseconds
 * @return ArrayList of {@link ClientScanResult}
 */
public ArrayList<ClientScanResult> getClientList(boolean onlyReachables, int reachableTimeout) {
    BufferedReader br = null;
    ArrayList<ClientScanResult> result = null;

    try {
        result = new ArrayList<ClientScanResult>();
        br = new BufferedReader(new FileReader("/proc/net/arp"));
        String line;
        while ((line = br.readLine()) != null) {
            String[] splitted = line.split(" +");

            if ((splitted != null) && (splitted.length >= 4)) {
                // Basic sanity check
                String mac = splitted[3];

                if (mac.matches("..:..:..:..:..:..")) {
                    boolean isReachable = InetAddress.getByName(splitted[0]).isReachable(reachableTimeout);
                    Log.e("WifiApManager", "getClientList: " + isReachable);
                    if (!onlyReachables || isReachable) {
                        result.add(new ClientScanResult(splitted[0], splitted[3], splitted[5], isReachable));
                    }
                }
            }
        }
    } catch (Exception e) {
        Log.e(this.getClass().toString(), e.getMessage());
    } finally {
        try {
            br.close();
        } catch (IOException e) {
            Log.e(this.getClass().toString(), e.getMessage());
        }
    }

    return result;
}
}