Building Simple Chat Client with Parse - meswapnilwagh/android_guides GitHub Wiki

public class ChatActivity extends AppCompatActivity {
    static final String TAG = ChatActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chat);
        // User login
        if (ParseUser.getCurrentUser() != null) { // start with existing user
            startWithCurrentUser();
        } else { // If not logged in, login as a new anonymous user
            login();
        }
    }
    
    // Get the userId from the cached currentUser object
    void startWithCurrentUser() {
        // TODO:
    }
    
    // Create an anonymous user using ParseAnonymousUtils and set sUserId 
    void login() {
        ParseAnonymousUtils.logIn(new LogInCallback() {
	    @Override
	    public void done(ParseUser user, ParseException e) {
                if (e != null) {
                    Log.e(TAG, "Anonymous login failed: ", e);
                } else {
                    startWithCurrentUser();
                }
            }
       });		
    }
}

public class ChatActivity extends AppCompatActivity {
...
    static final String USER_ID_KEY = "userId";
    static final String BODY_KEY = "body";

    EditText etMessage;
    Button btSend;

...

    // Get the userId from the cached currentUser object
    void startWithCurrentUser() {
        setupMessagePosting();
    }

    // Setup button event handler which posts the entered message to Parse
    void setupMessagePosting() {
        // Find the text field and button
        etMessage = (EditText) findViewById(R.id.etMessage);
        btSend = (Button) findViewById(R.id.btSend);
        // When send button is clicked, create message object on Parse
        btSend.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = etMessage.getText().toString();
                ParseObject message = ParseObject.create("Message");
                message.put(USER_ID_KEY, ParseUser.getCurrentUser().getObjectId());
                message.put(BODY_KEY, data);
                message.saveInBackground(new SaveCallback() {
                    @Override
                    public void done(ParseException e) {
                    	Toast.makeText(ChatActivity.this, "Successfully created message on Parse",
                             Toast.LENGTH_SHORT).show();
                    }
                });
                etMessage.setText(null);
            }
        });
    }
}

@ParseClassName("Message")
public class Message extends ParseObject {
    public static final String USER_ID_KEY = "userId";
    public static final String BODY_KEY = "body";

    public String getUserId() {
        return getString(USER_ID_KEY);
    }

    public String getBody() {
        return getString(BODY_KEY);
    }

    public void setUserId(String userId) {
        put(USER_ID_KEY, userId);
    }

    public void setBody(String body) {
        put(BODY_KEY, body);
    }
}}

public class ChatApplication extends Application {
	// ...
	public void onCreate() {
		super.onCreate();
		// Register your parse models here
		ParseObject.registerSubclass(Message.class);
		// Existing initialization happens after all classes are registered
	
                // For open-source Parse backend
                Parse.initialize(new Parse.Configuration.Builder(this)
                     .applicationId("YOUR_APPLICATION_ID") // should correspond to APP_ID env variable
                     .addNetworkInterceptor(new ParseLogInterceptor())
                     .server("https://myparseapp.herokuapp.com/parse/").build());
	}
}

...
void setupMessagePosting() {
        // Find the text field and button
        etMessage = (EditText) findViewById(R.id.etMessage);
        btSend = (Button) findViewById(R.id.btSend);
        // When send button is clicked, create message object on Parse
        btSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = etMessage.getText().toString();
                ParseObject message = ParseObject.create("Message");
                message.put(**Message.USER_ID_KEY**, ParseUser.getCurrentUser().getObjectId());
                message.put(**Message.BODY_KEY**, data);
                message.saveInBackground(new SaveCallback() {
                    @Override
                    public void done(ParseException e) {
                        Toast.makeText(ChatActivity.this, "Successfully created message on Parse",
                                Toast.LENGTH_SHORT).show();
                    }
                });
                etMessage.setText(null);
            }
        });
    }
...

public class ChatListAdapter extends ArrayAdapter<Message> {
    private String mUserId;

    public ChatListAdapter(Context context, String userId, List<Message> messages) {
        super(context, 0, messages);
        this.mUserId = userId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(getContext()).
                    inflate(R.layout.chat_item, parent, false);
            final ViewHolder holder = new ViewHolder();
            holder.imageOther = (ImageView)convertView.findViewById(R.id.ivProfileOther);
            holder.imageMe = (ImageView)convertView.findViewById(R.id.ivProfileMe);
            holder.body = (TextView)convertView.findViewById(R.id.tvBody);
            convertView.setTag(holder);
        }
        final Message message = getItem(position);
        final ViewHolder holder = (ViewHolder)convertView.getTag();
        final boolean isMe = message.getUserId().equals(mUserId);
        // Show-hide image based on the logged-in user.
        // Display the profile image to the right for our user, left for other users.
        if (isMe) {
            holder.imageMe.setVisibility(View.VISIBLE);
            holder.imageOther.setVisibility(View.GONE);
            holder.body.setGravity(Gravity.CENTER_VERTICAL | Gravity.RIGHT);
        } else {
            holder.imageOther.setVisibility(View.VISIBLE);
            holder.imageMe.setVisibility(View.GONE);
            holder.body.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
        }
        final ImageView profileView = isMe ? holder.imageMe : holder.imageOther;
        Picasso.with(getContext()).load(getProfileUrl(message.getUserId())).into(profileView);
        holder.body.setText(message.getBody());
        return convertView;
    }

    // Create a gravatar image based on the hash value obtained from userId
    private static String getProfileUrl(final String userId) {
        String hex = "";
        try {
            final MessageDigest digest = MessageDigest.getInstance("MD5");
            final byte[] hash = digest.digest(userId.getBytes());
            final BigInteger bigInt = new BigInteger(hash);
            hex = bigInt.abs().toString(16);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "http://www.gravatar.com/avatar/" + hex + "?d=identicon";
    }

    final class ViewHolder {
        public ImageView imageOther;
        public ImageView imageMe;
        public TextView body;
    }
}

public class ChatActivity extends AppCompatActivity {
...
    ListView lvChat;
    ArrayList<Message> mMessages;
    ChatListAdapter mAdapter;
    // Keep track of initial load to scroll to the bottom of the ListView
    boolean mFirstLoad;
	
    // Setup message field and posting
    void setupMessagePosting() {
        // Find the text field and button
        etMessage = (EditText) findViewById(R.id.etMessage);
        btSend = (Button) findViewById(R.id.btSend);
        lvChat = (ListView) findViewById(R.id.lvChat);
        mMessages = new ArrayList<>();
        // Automatically scroll to the bottom when a data set change notification is received and only if the last item is already visible on screen. Don't scroll to the bottom otherwise.
        lvChat.setTranscriptMode(1);
        mFirstLoad = true;
        final String userId = ParseUser.getCurrentUser().getObjectId();
        mAdapter = new ChatListAdapter(ChatActivity.this, userId, mMessages);
        lvChat.setAdapter(mAdapter);
        // When send button is clicked, create message object on Parse
        btSend.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String data = etMessage.getText().toString();
                ParseObject message = ParseObject.create("Message");
                message.put(Message.USER_ID_KEY, userId);
                message.put(Message.BODY_KEY, data);
                message.saveInBackground(new SaveCallback() {
                    @Override
                    public void done(ParseException e) {
                        Toast.makeText(ChatActivity.this, "Successfully created message on Parse",
                                Toast.LENGTH_SHORT).show();
                        refreshMessages();
                    }
                });
                etMessage.setText(null);
            }
        });
    }

    // Query messages from Parse so we can load them into the chat adapter
    void refreshMessages() {
        // TODO:
    }
...
}

public class ChatActivity extends AppCompatActivity {
...
    static final int MAX_CHAT_MESSAGES_TO_SHOW = 50;
...
    // Query messages from Parse so we can load them into the chat adapter
    void refreshMessages() {
        // Construct query to execute
        ParseQuery<Message> query = ParseQuery.getQuery(Message.class);
        // Configure limit and sort order
        query.setLimit(MAX_CHAT_MESSAGES_TO_SHOW);
        query.orderByAscending("createdAt");
        // Execute query to fetch all messages from Parse asynchronously
        // This is equivalent to a SELECT query with SQL
        query.findInBackground(new FindCallback<Message>() {
            public void done(List<Message> messages, ParseException e) {
                if (e == null) {
                    mMessages.clear();
                    mMessages.addAll(messages);
                    mAdapter.notifyDataSetChanged(); // update adapter
                    // Scroll to the bottom of the list on initial load
                    if (mFirstLoad) {
                        lvChat.setSelection(mAdapter.getCount() - 1);
                        mFirstLoad = false;
                    }
                } else {
                    Log.e("message", "Error Loading Messages" + e);
                }
            }
        });
    }
}

...

// Create a handler which can run code periodically
static final int POLL_INTERVAL = 100; // milliseconds
Handler mHandler = new Handler();  // android.os.Handler
Runnable mRefreshMessagesRunnable = new Runnable() {
    @Override
    public void run() {
       refreshMessages();
       mHandler.postDelayed(this, POLL_INTERVAL);
    }
};

...

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_chat);
    if (ParseUser.getCurrentUser() != null) {
        startWithCurrentUser();
    } else {
    	login();
    }
    mHandler.postDelayed(mRefreshMessagesRunnable, POLL_INTERVAL);
}