Comprendre le BluetoothChat de Google Sample

Bonjour,

Je suis en train de développer une petite application Bluetooth en m'aidant du BluetoothChat sample de Google mais je suis encore débutant.
J'aurais besoin d'un peu d'aides pour comprendre les lignes de codes :

J'avais une première question : que signifie private static final String TAG = "BluetoothChatFragment"; ? J'ai vu dans des nombreux forums que cette ligne concernait les logs qu'on allait mettre ensuite mais je ne comprend pas vraiment ...

Merci pour votre aide

Voici le code du BluetoothChatFragment :

Code:

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/**  * This fragment controls Bluetooth to communicate with other devices.  */ public class BluetoothChatFragment extends Fragment {   private static final String TAG = "BluetoothChatFragment";   // Intent request codes private static final int REQUEST_CONNECT_DEVICE_SECURE = 1; private static final int REQUEST_CONNECT_DEVICE_INSECURE = 2; private static final int REQUEST_ENABLE_BT = 3;   // Layout Views private ListView mConversationView; private EditText mOutEditText; private Button mSendButton;   /**      * Name of the connected device      */ private String mConnectedDeviceName = null;   /**      * Array adapter for the conversation thread      */ private ArrayAdapter<String> mConversationArrayAdapter;   /**      * String buffer for outgoing messages      */ private StringBuffer mOutStringBuffer;   /**      * Local Bluetooth adapter      */ private BluetoothAdapter mBluetoothAdapter = null;   /**      * Member object for the chat services      */ private BluetoothChatService mChatService = null;   @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); // Get local Bluetooth adapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();   // If the adapter is null, then Bluetooth is not supported if (mBluetoothAdapter == null) { FragmentActivity activity = getActivity(); Toast.makeText(activity, "Bluetooth is not available", Toast.LENGTH_LONG).show(); activity.finish(); //the method onDestroy() is executed and dismisses any dialogs the activity was managing, closes any open search dialo } }     @Override public void onStart() { super.onStart(); // ??? // If BT is not on, request that it be enabled. // setupChat() will then be called during onActivityResult if (!mBluetoothAdapter.isEnabled()) { /*To enable bluetooth adapter you can start a system preference activity using the   BluetoothAdapter.ACTION_REQUEST_ENABLE static constants as a startActivityForResult   action string*/ Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); startActivityForResult(enableIntent, REQUEST_ENABLE_BT); // Otherwise, setup the chat session } else if (mChatService == null) { setupChat(); } }   @Override public void onDestroy() { super.onDestroy(); if (mChatService != null) { mChatService.stop(); } }   @Override public void onResume() { super.onResume();   // Performing this check in onResume() covers the case in which BT was // not enabled during onStart(), so we were paused to enable it... // onResume() will be called when ACTION_REQUEST_ENABLE activity returns. if (mChatService != null) { // Only if the state is STATE_NONE, do we know that we haven't started already if (mChatService.getState() == BluetoothChatService.STATE_NONE) { // Start the Bluetooth chat services mChatService.start(); } } }   @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { return inflater.inflate(R.layout.fragment_bluetooth_chat, container, false); }   @Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { mConversationView = (ListView) view.findViewById(R.id.in); mOutEditText = (EditText) view.findViewById(R.id.edit_text_out); mSendButton = (Button) view.findViewById(R.id.button_send); }   /**      * Set up the UI and background operations for chat.      */ private void setupChat() { Log.d(TAG, "setupChat()");   // Initialize the array adapter for the conversation thread mConversationArrayAdapter = new ArrayAdapter<String>(getActivity(), R.layout.message);   mConversationView.setAdapter(mConversationArrayAdapter);   // Initialize the compose field with a listener for the return key mOutEditText.setOnEditorActionListener(mWriteListener);   // Initialize the send button with a listener that for click events mSendButton.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // Send a message using content of the edit text widget View view = getView(); if (null != view) { TextView textView = (TextView) view.findViewById(R.id.edit_text_out); String message = textView.getText().toString(); sendMessage(message); } } });   // Initialize the BluetoothChatService to perform bluetooth connections mChatService = new BluetoothChatService(getActivity(), mHandler);   // Initialize the buffer for outgoing messages mOutStringBuffer = new StringBuffer(""); }   /**      * Makes this device discoverable for 300 seconds (5 minutes).      */ private void ensureDiscoverable() { if (mBluetoothAdapter.getScanMode() != BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) { Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE); discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300); startActivity(discoverableIntent); } }   /**      * Sends a message.      *      * @param message A string of text to send.      */ private void sendMessage(String message) { // Check that we're actually connected before trying anything if (mChatService.getState() != BluetoothChatService.STATE_CONNECTED) { Toast.makeText(getActivity(), R.string.not_connected, Toast.LENGTH_SHORT).show(); return; }   // Check that there's actually something to send if (message.length() > 0) { // Get the message bytes and tell the BluetoothChatService to write byte[] send = message.getBytes(); mChatService.write(send);   // Reset out string buffer to zero and clear the edit text field mOutStringBuffer.setLength(0); mOutEditText.setText(mOutStringBuffer); } }   /**      * The action listener for the EditText widget, to listen for the return key      */ private TextView.OnEditorActionListener mWriteListener = new TextView.OnEditorActionListener() { public boolean onEditorAction(TextView view, int actionId, KeyEvent event) { // If the action is a key-up event on the return key, send the message if (actionId == EditorInfo.IME_NULL && event.getAction() == KeyEvent.ACTION_UP) { String message = view.getText().toString(); sendMessage(message); } return true; } };   /**      * Updates the status on the action bar.      *      * @param resId a string resource ID      */ private void setStatus(int resId) { FragmentActivity activity = getActivity(); if (null == activity) { return; } final ActionBar actionBar = activity.getActionBar(); if (null == actionBar) { return; } actionBar.setSubtitle(resId); }   /**      * Updates the status on the action bar.      *      * @param subTitle status      */ private void setStatus(CharSequence subTitle) { FragmentActivity activity = getActivity(); if (null == activity) { return; } final ActionBar actionBar = activity.getActionBar(); if (null == actionBar) { return; } actionBar.setSubtitle(subTitle); }   /**      * The Handler that gets information back from the BluetoothChatService      */ private final Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { FragmentActivity activity = getActivity(); switch (msg.what) { case Constants.MESSAGE_STATE_CHANGE: switch (msg.arg1) { case BluetoothChatService.STATE_CONNECTED: setStatus(getString(R.string.title_connected_to, mConnectedDeviceName)); mConversationArrayAdapter.clear(); break; case BluetoothChatService.STATE_CONNECTING: setStatus(R.string.title_connecting); break; case BluetoothChatService.STATE_LISTEN: case BluetoothChatService.STATE_NONE: setStatus(R.string.title_not_connected); break; } break; case Constants.MESSAGE_WRITE: byte[] writeBuf = (byte[]) msg.obj; // construct a string from the buffer String writeMessage = new String(writeBuf); mConversationArrayAdapter.add("Me: " + writeMessage); break; case Constants.MESSAGE_READ: byte[] readBuf = (byte[]) msg.obj; // construct a string from the valid bytes in the buffer String readMessage = new String(readBuf, 0, msg.arg1); mConversationArrayAdapter.add(mConnectedDeviceName + ": " + readMessage); break; case Constants.MESSAGE_DEVICE_NAME: // save the connected device's name mConnectedDeviceName = msg.getData().getString(Constants.DEVICE_NAME); if (null != activity) { Toast.makeText(activity, "Connected to " + mConnectedDeviceName, Toast.LENGTH_SHORT).show(); } break; case Constants.MESSAGE_TOAST: if (null != activity) { Toast.makeText(activity, msg.getData().getString(Constants.TOAST), Toast.LENGTH_SHORT).show(); } break; } } };   public void onActivityResult(int requestCode, int resultCode, Intent data) { switch (requestCode) { case REQUEST_CONNECT_DEVICE_SECURE: // When DeviceListActivity returns with a device to connect if (resultCode == Activity.RESULT_OK) { connectDevice(data, true); } break; case REQUEST_CONNECT_DEVICE_INSECURE: // When DeviceListActivity returns with a device to connect if (resultCode == Activity.RESULT_OK) { connectDevice(data, false); } break; case REQUEST_ENABLE_BT: // When the request to enable Bluetooth returns if (resultCode == Activity.RESULT_OK) { // Bluetooth is now enabled, so set up a chat session setupChat(); } else { // User did not enable Bluetooth or an error occurred Log.d(TAG, "BT not enabled"); Toast.makeText(getActivity(), R.string.bt_not_enabled_leaving, Toast.LENGTH_SHORT).show(); getActivity().finish(); } } }   /**      * Establish connection with other device      *      * @param data   An {@link Intent} with {@link DeviceListActivity#EXTRA_DEVICE_ADDRESS} extra.      * @param secure Socket Security type - Secure (true) , Insecure (false)      */ private void connectDevice(Intent data, boolean secure) { // Get the device MAC address String address = data.getExtras() .getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS); // Get the BluetoothDevice object BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address); // Attempt to connect to the device mChatService.connect(device, secure); }   @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.bluetooth_chat, menu); }   @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.secure_connect_scan: { // Launch the DeviceListActivity to see devices and do scan Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class); startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_SECURE); return true; } case R.id.insecure_connect_scan: { // Launch the DeviceListActivity to see devices and do scan Intent serverIntent = new Intent(getActivity(), DeviceListActivity.class); startActivityForResult(serverIntent, REQUEST_CONNECT_DEVICE_INSECURE); return true; } case R.id.discoverable: { // Ensure this device is discoverable by others ensureDiscoverable(); return true; } } return false; }   }

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Je me posais également la question : dans la méthode onStart(), pourquoi doit - on se référer à l'ancienne méthode hérité onStart() ? ( par l'intermédiaire de super.onStart() )