public class MainActivity extends Activity {

    private static final String TAG = MainActivity.class.getSimpleName();

    private WifiP2pManager wifiP2pManager;
    private WifiP2pManager.Channel channel;
    private BroadcastReceiver broadcastReceiver;

    private Button button1;
    private Button button2;
    private Button button3;
    private TextView result;
    private EditText editText;

    private HandlerThread handlerThread;
    private Handler handler;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        result = findViewById(R.id.result);
        button1 = findViewById(R.id.button1);
        button2 = findViewById(R.id.button2);
        button3 = findViewById(R.id.button3);
        editText = findViewById(R.id.edit1);


        handlerThread = new HandlerThread(TAG);
        handlerThread.start();
        handler = new Handler(handlerThread.getLooper());

        init();

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        wifiP2pManager.createGroup(channel, new WifiP2pManager.ActionListener() {
                            @Override
                            public void onSuccess() {
                                Log.d(TAG, "onSuccess");
                            }

                            @Override
                            public void onFailure(int reason) {
                                Log.d(TAG, "onFailure, reason: " + reason);
                            }
                        });
                    }
                });

            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        wifiP2pManager.discoverPeers(channel, new WifiP2pManager.ActionListener() {
                            @Override
                            public void onSuccess() {
                                Log.d(TAG, "discovery onSuccess");
                            }

                            @Override
                            public void onFailure(int reason) {
                                Log.d(TAG, "discovery onFailure, reason: " + reason);
                            }
                        });

                    }
                });
            }
        });

        button3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                    }
                });

            }
        });
    }

    private void init() {

        wifiP2pManager = (WifiP2pManager) getSystemService(WIFI_P2P_SERVICE);
        channel = wifiP2pManager.initialize(this, getMainLooper(), new WifiP2pManager.ChannelListener() {
            @Override
            public void onChannelDisconnected() {
                Log.d(TAG, "onChannelDisconnected");
            }
        });
        broadcastReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, final Intent intent) {
                if (intent.getAction() == null) {
                    return;
                }

                switch (intent.getAction()) {
                    case WifiP2pManager.WIFI_P2P_DISCOVERY_CHANGED_ACTION:
                        Log.d(TAG, "onReceive, discovery changed action");
                        break;
                    case WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION:
                        NetworkInfo networkInfo = intent.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);
                        if (networkInfo.isConnected()) {
                            wifiP2pManager.requestConnectionInfo(channel, new WifiP2pManager.ConnectionInfoListener() {
                                @Override
                                public void onConnectionInfoAvailable(WifiP2pInfo info) {
                                    Log.d(TAG, "onConnectionInfoAvailable, info: " + info.toString());
                                }
                            });
                            Log.e(TAG, "device is connected");
                        } else {
                            Log.e(TAG, "device is disconnected");
                        }
                        break;
                    case WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION:
                        wifiP2pManager.requestPeers(channel, new WifiP2pManager.PeerListListener() {
                            @Override
                            public void onPeersAvailable(WifiP2pDeviceList peers) {
                                Collection<WifiP2pDevice> list = peers.getDeviceList();
                                Log.d(TAG, "onPeersAvailable, device size: " + list.size());
                                Iterator iterator = list.iterator();
                                while (iterator.hasNext()){
                                    WifiP2pDevice device = (WifiP2pDevice) iterator.next();
                                    Log.d(TAG, "onPeersAvailable, device: " + device.toString());
                                }
                            }
                        });
                        break;
                    case WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION:
                        Log.d(TAG, "onReceive, this device changed action");
                        break;
                    case WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION:
                        int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
                        if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
                            Log.d(TAG, "onReceive p2p is enable");
                        } else {
                            Log.d(TAG, "onReceive p2p is not enable");
                        }
                        break;
                }
            }
        };

        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_DISCOVERY_CHANGED_ACTION);
        registerReceiver(broadcastReceiver, intentFilter);

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        wifiP2pManager.removeGroup(channel, new WifiP2pManager.ActionListener() {
            @Override
            public void onSuccess() {
                Log.d(TAG, "remove onSuccess");
            }

            @Override
            public void onFailure(int reason) {
                Log.d(TAG, "remove onFailure, reason: " + reason);
            }
        });
    }
}