getApplicationContext（）使用Belkin WeMo SDK返回null

Question

我试图在Android Studio上创建一个应用程序，该应用程序使用Belkin WeMo SDK来控制我家周围的设备。我在onCreate方法中初始化了mWeMoSDKContext对象，如文档中所示。但是，当我去运行应用程序时，我一直得到NullPointerException并在调试后发现它在我初始化对象的行中。有没有什么办法解决这一问题？此外，对应用程序的任何建议也将不胜感激！

public class MyActivity extends AppCompatActivity implements NotificationListener {

    private WeMoSDKContext mWeMoSDKContext = null;
    private EditText devicesDisp = null;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        Button onButton = (Button)findViewById(R.id.button);
        Button offButton = (Button)findViewById(R.id.button2);
        devicesDisp = (EditText)findViewById(R.id.textView2);
        TextView device = (TextView) findViewById(R.id.textView);


        **mWeMoSDKContext = new WeMoSDKContext(getApplicationContext());
        mWeMoSDKContext.addNotificationListener(this);**



    }


    public class TextTask extends AsyncTask <String, String, String>{

        @Override
        protected String doInBackground(String... params) {

        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            mWeMoSDKContext.refreshListOfWeMoDevicesOnLAN();

        }
    }

    public void onNotify(final String event, final String udn) {

        ArrayList<String> udns = mWeMoSDKContext.getListOfWeMoDevicesOnLAN();
        int length = udns.size();
        if (event.equals(WeMoSDKContext.REFRESH_LIST)) {
                if(udns.size() == 0){
                    devicesDisp.setText("No Devices Detected");
                }
                else {
                    for (int i = 0; i < length; i++) {
                        WeMoDevice device = mWeMoSDKContext.getWeMoDeviceByUDN(udns.get(i));
                        String tempName = device.getFriendlyName();
                        devicesDisp.setText(tempName);
                    }
                }

            }
        }
        else if(event.equals(WeMoSDKContext.SET_STATE)) {
            int numDevices = udns.size();
            if(hourlyPrice > hourlyPriceLimit) {
                for (int i = 0; i < numDevices; i++) {
                    String checkState = "WEMO_DEVICE_OFF";
                    WeMoDevice checkDevice = mWeMoSDKContext.getWeMoDeviceByUDN(udns.get(i));
                    if (!checkDevice.getState().equalsIgnoreCase("WEMO_DEVICE_OFF")){
                        devicesDisp.setText("Device state not changed for" + checkDevice);
                    }
                }
            }
            else{
                for (int i = 0; i < numDevices; i++) {
                    String checkState = "WEMO_DEVICE_ON";
                    WeMoDevice checkDevice = mWeMoSDKContext.getWeMoDeviceByUDN(udns.get(i));
                    if (!checkDevice.getState().equalsIgnoreCase("WEMO_DEVICE_ON")){
                        devicesDisp.setText("Device state not changed for" + checkDevice);
                    }
                }
            }
        }

    }

    public void turnON(View view){
        ArrayList<String> devices = mWeMoSDKContext.getListOfWeMoDevicesOnLAN();
        int length = devices.size();
        for(int i = 0; i < length; i++){
            String state = "WEMO_DEVICE_ON";
            WeMoDevice deviceState = mWeMoSDKContext.getWeMoDeviceByUDN(devices.get(i));
            String type = deviceState.getType();
            if (type.equals(WeMoDevice.SWITCH) || type.equals(WeMoDevice.INSIGHT)) {
                mWeMoSDKContext.setDeviceState(state, devices.get(i));
            }
        }
    }


    public void turnOFF(View view){
        ArrayList<String> devices = mWeMoSDKContext.getListOfWeMoDevicesOnLAN();
        int length = devices.size();
        for(int i = 0; i < length; i++){
            String state = "WEMO_DEVICE_OFF";
            WeMoDevice deviceState = mWeMoSDKContext.getWeMoDeviceByUDN(devices.get(i));
            String type = deviceState.getType();
            if (type.equals(WeMoDevice.SWITCH) || type.equals(WeMoDevice.INSIGHT)) {
                mWeMoSDKContext.setDeviceState(state, devices.get(i));
            }
        }
    }

    protected void onDestroy() {
        super.onDestroy();
        mWeMoSDKContext.stop();
    }


}

更新：这里是错误的堆栈跟踪

java.lang.NullPointerException: Attempt to get length of null array at org.cybergarage.upnp.ControlPoint.start(ControlPoint.java:976) at org.cybergarage.upnp.ControlPoint.start(ControlPoint.java:1051) at com.belkin.wemo.localsdk.WeMoSDKContext$1.run(WeMoSDKContext.java:125) at java.lang.Thread.run(Thread.java:818)