non-static variable discoveryListener cannot be referenced from a static context

Question

I want to understand why this problem take place while calling Nsdmanager from a static method, here below the code

public void initializeDiscoveryListener() {

         // Instantiate a new DiscoveryListener

           discoveryListener = new NsdManager.DiscoveryListener() {

             // Called as soon as service discovery begins.
             @Override
             public void onDiscoveryStarted(String regType) {
                 Log.d(TAG, "Service discovery started");
             }

             @Override
             public void onServiceFound(NsdServiceInfo service) {
                 // A service was found! Do something with it.
                 Log.d(TAG, "Service discovery success" + service);
                 if (!service.getServiceType().equals(SERVICE_TYPE)) {
                     // Service type is the string containing the protocol and
                     // transport layer for this service.
                     Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
                 } else if (service.getServiceName().equals(serviceName)) {
                     // The name of the service tells the user what they'd be
                     // connecting to. It could be "Bob's Chat App".
                     Log.d(TAG, "Same machine: " + serviceName);
                 } else if (service.getServiceName().contains("NsdChat")){
                    // nsdManager.resolveService(service, resolveListener);
                 }
             }

             @Override
             public void onServiceLost(NsdServiceInfo service) {
                 // When the network service is no longer available.
                 // Internal bookkeeping code goes here.
                 Log.e(TAG, "service lost: " + service);
             }

             @Override
             public void onDiscoveryStopped(String serviceType) {
                 Log.i(TAG, "Discovery stopped: " + serviceType);
             }

             @Override
             public void onStartDiscoveryFailed(String serviceType, int errorCode) {
                 Log.e(TAG, "Discovery failed: Error code:" + errorCode);
                 nsdManager.stopServiceDiscovery(this);
             }

             @Override
             public void onStopDiscoveryFailed(String serviceType, int errorCode) {
                 Log.e(TAG, "Discovery failed: Error code:" + errorCode);
                 nsdManager.stopServiceDiscovery(this);
             }
         };
     }

 public static void discover(){
     System.out.println("discoverServices");

     nsdManager.discoverServices("_http._tcp.", NsdManager.PROTOCOL_DNS_SD, discoveryListener);


 }
     //nsdManager = (NsdManager)c.getSystemService(Context.NSD_SERVICE);






}

I got the problem below:

** :\ProgQt\build-app-Android_for_armeabi_v7a_arm64_v8a_x86_x86_64_Clang_Qt_5_15_0_for_Android-Debug\android-build\src\org\qtproject\example\musiclist\MusicList.java:188: error: non-static variable discoveryListener cannot be referenced from a static context nsdManager.discoverServices("_http._tcp.", NsdManager.PROTOCOL_DNS_SD, discoveryListener);**