Vfrdtyky

I'm practicing multi-client networking using a Java Server and Android clients. I have done this with Java clients before so I adapted my solution mostly around what I know in Java using multithreading. Which is extending a thread for each client connection created. I usually have a separate ClientConnection class in Java but here I used a protected inner class.

This solution works but someone mentioned to me that I might want to do this with AsyncTask rather. What benefits would using AsyncTask offer rather than extending a thread the way I have done here?

Please note I am not asking for any code or how I would go about doing it. Just what benefits it would offer over this method.

Client Layout

<RelativeLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    android:paddingBottom="@dimen/activity_vertical_margin"

    tools:context="za.ac.nmu.wrap302.jan2015.MainActivity">



<LinearLayout

        android:orientation="vertical"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:id="@+id/loginPanel"

        android:layout_alignParentBottom="true">

    <EditText

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:id="@+id/etHandle"

            android:layout_alignParentTop="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentStart="true"

            android:layout_alignParentRight="true"

            android:layout_alignParentEnd="true"/>

    <Button

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Connect"

            android:id="@+id/btnConnect"

            android:layout_below="@+id/etHandle"

            android:layout_alignParentLeft="true"

            android:layout_alignParentStart="true"

            android:layout_alignRight="@+id/etHandle"

            android:layout_alignEnd="@+id/etHandle"/>

</LinearLayout>

<LinearLayout

        android:orientation="vertical"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:id="@+id/chatPanel"

        android:visibility="gone">

    <ListView

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:id="@+id/lvMessages"

            android:layout_below="@+id/btnConnect"

            android:layout_alignParentLeft="true"

            android:layout_alignParentStart="true"

            android:layout_above="@+id/txtMessage"/>

    <Button

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Change Room"

            android:id="@+id/btnRoom"/>

    <EditText

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:id="@+id/txtMessage"

            android:layout_above="@+id/btnDisconnect"

            android:layout_alignParentLeft="true"

            android:layout_alignParentStart="true"

            android:layout_alignRight="@+id/btnDisconnect"

            android:layout_alignEnd="@+id/btnDisconnect"/>

</LinearLayout>

<LinearLayout

        android:background="?android:colorBackground"

        android:orientation="vertical"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:id="@+id/roomPanel"

        android:visibility="gone">

    <Button

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:text="Disconnect"

            android:id="@+id/btnDisconnect"

            android:layout_alignParentBottom="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentStart="true"

            android:layout_alignRight="@+id/lvMessages"

            android:layout_alignEnd="@+id/lvMessages"/>

    <ListView

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:id="@+id/lvRooms"/>

</LinearLayout>

Client Code

public class MainActivity extends AppCompatActivity {

EditText etHandle;

ConnectionThread connectionThread;

private ArrayList<String> messages;

private ArrayAdapter<String> adapter;



private ArrayList<String> rooms;

private ArrayAdapter<String> roomsAdapter;



private static final String SET_HANDLE = "#SetHandle";

private static final String SEND_MESSAGE = "#SendMessage";

private static final String DISCONNECT = "#Disconnect";

private static final String JOIN_ROOM = "#JoinRoom";

private static final String LIST_ROOMS = "#ListRooms";



ListView lvMessages;

ListView lvRooms;



EditText textMessage;

Button btnConnect;

Button btnDisconnect;

Button btnRoom;

LinearLayout chatPanel, roomPanel, loginPanel;



@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);



    etHandle = (EditText) findViewById(R.id.etHandle);

    lvMessages = (ListView) findViewById(R.id.lvMessages);

    textMessage = (EditText) findViewById(R.id.txtMessage);

    btnConnect = (Button) findViewById(R.id.btnConnect);

    btnDisconnect = (Button) findViewById(R.id.btnDisconnect);

    chatPanel = (LinearLayout) findViewById(R.id.chatPanel);

    roomPanel = (LinearLayout) findViewById(R.id.roomPanel);

    loginPanel = (LinearLayout) findViewById(R.id.loginPanel);

    lvRooms = (ListView) findViewById(R.id.lvRooms);

    btnRoom = (Button) findViewById(R.id.btnRoom);



    messages = new ArrayList<String>();

    adapter = new ArrayAdapter<String>(this,

            android.R.layout.simple_selectable_list_item, messages);

    lvMessages.setAdapter(adapter);



    rooms = new ArrayList<String>();

    roomsAdapter = new ArrayAdapter<String>(this,

            android.R.layout.simple_selectable_list_item, rooms);

    lvRooms.setAdapter(roomsAdapter);



    btnConnect.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View view) {

            connectionThread = new ConnectionThread(etHandle.getText().toString());

            connectionThread.start();

        }

    });



    btnDisconnect.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View view) {

            Thread out = new Thread(new Runnable() {

                @Override

                public void run() {

                    try {

                        connectionThread.out.writeUTF(DISCONNECT);

                    } catch (IOException e) {

                        e.printStackTrace();

                    }

                }

            });

            out.start();

            hideRoomScreen();

            showLoginScreen();

        }

    });



    btnRoom.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View view) {

            showRoomScreen();

            Thread out = new Thread(new Runnable() {

                @Override

                public void run() {

                    try {

                        connectionThread.out.writeUTF(LIST_ROOMS);

                    } catch (IOException e) {

                        e.printStackTrace();

                    }

                }

            });

            out.start();

        }

    });



    textMessage.setOnKeyListener(new View.OnKeyListener() {

        @Override

        public boolean onKey(View v, int keyCode, KeyEvent event) {

            if ((keyCode == KeyEvent.KEYCODE_ENTER) && (event.getAction() == KeyEvent.ACTION_DOWN)) {

                final String text = textMessage.getText().toString();

                Thread out = new Thread(new Runnable() {

                    @Override

                    public void run() {

                        try {

                            connectionThread.out.writeUTF(SEND_MESSAGE);

                            connectionThread.out.writeUTF(text);

                        } catch (IOException e) {

                            e.printStackTrace();

                        }

                    }

                });

                out.start();

                textMessage.getText().clear();

                return true;

            }

            return false;

        }

    });



    lvRooms.setOnItemClickListener(new AdapterView.OnItemClickListener() {

        @Override

        public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {

            final String roomName = roomsAdapter.getItem(i);

            Thread out = new Thread(new Runnable() {

                @Override

                public void run() {

                    try {

                        connectionThread.out.writeUTF(JOIN_ROOM);

                        connectionThread.out.writeUTF(roomName);

                    } catch (IOException e) {

                        e.printStackTrace();

                    }

                }

            });

            out.start();

            hideRoomScreen();

            showChatScreen();

        }

    });

}



public void addMessage(String message) {

    adapter.add(message);

    lvMessages.setSelection(adapter.getCount() - 1);

}



public void addRoom(final String roomName){

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            roomsAdapter.add(roomName);

        }

    });

}



protected class ConnectionThread extends Thread {

    Socket connection;

    DataInputStream in;

    DataOutputStream out;

    String handle;

    boolean connected;



    public ConnectionThread(String name) {

        handle = name;

    }



    @Override

    public void run() {

        try {

            connection = new Socket("10.0.0.10", 1234);

            connected = true;



            in = new DataInputStream(connection.getInputStream());

            out = new DataOutputStream(connection.getOutputStream());



            out.writeUTF(handle);



            hideLoginScreen();

            btnRoom.callOnClick();



            String command = "";

            while (connected) {

                command = in.readUTF();

                switch (command) {

                    case SEND_MESSAGE:

                        final String user = in.readUTF();

                        final String message = in.readUTF();

                        runOnUiThread(new Runnable() {

                            @Override

                            public void run() {

                                addMessage(user + ": " + message);

                            }

                        });

                        break;

                    case DISCONNECT:

                        showLoginScreen();

                        connected = false;

                        break;

                    case LIST_ROOMS:

                        int count = in.readInt();

                        runOnUiThread(new Runnable() {

                            @Override

                            public void run() {

                                roomsAdapter.clear();

                            }

                        });

                        for(int i = 0; i < count; i++){

                            String roomName = in.readUTF();

                            addRoom(roomName);

                        }

                        break;

                }

            }



        } catch (IOException e) {

            e.printStackTrace();

        }



    }

}



private void showLoginScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            loginPanel.setVisibility(View.VISIBLE);

        }

    });

}



private void hideLoginScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            loginPanel.setVisibility(View.GONE);

        }

    });

}



private void showChatScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            chatPanel.setVisibility(View.VISIBLE);

        }

    });

}



private void hideChatScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            chatPanel.setVisibility(View.GONE);

        }

    });

}



private void showRoomScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            roomPanel.setVisibility(View.VISIBLE);

        }

    });

}



private void hideRoomScreen() {

    runOnUiThread(new Runnable() {

        @Override

        public void run() {

            roomPanel.setVisibility(View.GONE);

        }

    });

}

}

AsyncTask was not designed to remain active and to receive commands, so I'm not agree with who suggest to use it.
You need a Thread that remains active for an undetermined amount of time and that receive commands. It's physically possible to use AsyncTask in that similar way but this case is similar to one that uses a Component for a complete different thing, like when using a TextView to display images (by substitute common ImageView and manually draw on TextView): it's possible but....the question is: "WHY?"

There isn't any advantage by using it.