一定时间后如何结束wifi扫描任务

Question

在我的应用程序中，我正在使用WifiManger扫描附近的网络。另外，我正在使用广播接收器来分析扫描结果。我正在寻找特定的网络，所以如果30秒后我没有找到我要寻找的任何网络，我想停止扫描。我该如何设置时间限制？

这是我的广播接收器的代码：

class IoTDevicesReceiver extends BroadcastReceiver{

    @Override
    public void onReceive(Context context, Intent intent) {

        wifiList = wifi.getScanResults();
        netCount = wifiList.size();
        Log.e("Wifi", "Total wifi networks " + netCount);

        new Thread(new Runnable() {
            @Override
            public void run() {

                try{
                    networks.clear();
                    netCount -= 1;
                    while(netCount >= 0){

                        if(wifiList.get(netCount).SSID.contains("Type I") ||
                                wifiList.get(netCount).SSID.contains("Type II")) {

                            boolean isSecured = (wifiList.get(netCount).capabilities.contains("WEP") || wifiList.get(netCount).capabilities.contains("WPA"));
                            String encryptionType;
                            if(wifiList.get(netCount).capabilities.contains("WEP"))
                                encryptionType = "WEP";
                            else if(wifiList.get(netCount).capabilities.contains("WPA"))
                                encryptionType = "WPA";
                            else
                                encryptionType = "NONE";

                            Network network = new Network(wifiList.get(netCount).SSID.toString(),
                                    String.valueOf(wifiList.get(netCount).level), encryptionType, !isSecured);
                            Log.d("WiFi", network.getNetworkName());
                            networks.add(network);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    mAdapter.notifyDataSetChanged();
                                    mProgressbar.setVisibility(View.GONE);
                                    mWaitMessage.setVisibility(View.GONE);
                                }
                            });
                        }
                        netCount -= 1;
                    }
                }
                catch (Exception e){
                    Log.d("Wifi", e.getMessage());
                }
            }
        }).start();
    }
}

我使用这种方法开始扫描：

private void startWifiScanning()
{
        wifi.startScan();
}