Java server- Android socket connection

Java server- Android socket connection - android

My goal is to create Java application which would be server, and Android(client) socket connection, and make Android phone listen to my commands send from a server. My question is, how should i make my Android phone always listen for incoming commands(Strings) pushed from Java application. What is a best choice ? Thread, Service ?
Here is my code : Server in java:
public class Server extends JFrame {
private JTextField userText;
private JTextArea chatWindow;
private ObjectOutputStream output;
private ObjectInputStream input;
// private DataInputStream input;
private Socket connection;
ServerSocket server;
public Server() {
super("GUI");
userText = new JTextField();
userText.setEditable(false);
userText.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
sendMessage(e.getActionCommand());
userText.setText("");
}
});
add(userText, BorderLayout.NORTH);
chatWindow = new JTextArea();
add(new JScrollPane(chatWindow), BorderLayout.CENTER);
setSize(300, 150);
setVisible(true);
}
// connect to server
public void startRunning() {
try {
server = new ServerSocket(9000, 100);
while (true) {
try {
waitForConnection();
setupStreams();
whileChatting();
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (EOFException e) {
showMessage("\n Connection lost");
} catch (IOException e) {
e.printStackTrace();
} finally {
closeCrap();
}
}
// connect to server
private void waitForConnection() throws IOException {
showMessage(" \nWaiting for connection \n");
connection = server.accept();
showMessage(" now connected to "
+ connection.getInetAddress().getHostName());
}
private void setupStreams() throws IOException {
showMessage("\n Setting up streams \n");
output = new ObjectOutputStream(connection.getOutputStream());
output.flush();
// input = new DataInputStream(connection.getInputStream());
input = new ObjectInputStream(connection.getInputStream());
showMessage(" Streams are good \n");
}
private void whileChatting() throws IOException {
ableToType(true);
String message = "You are now connected ";
sendMessage(message);
do {// have conversation
try {
message = (String) input.readObject();
// message = (String) input.readLine();
showMessage("\n" + message);
} catch (ClassNotFoundException e) {
showMessage("Dont know that object type ");
// TODO: handle exception
}
} while (!message.equals("server - end"));
}
// close everything
private void closeCrap() {
showMessage("\n Closing..");
ableToType(false);
try {
output.close();
input.close();
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
// send message to server
private void sendMessage(String message) {
try {
output.writeObject("CLIENT - " + message);
output.flush();
showMessage("\n" + "CLIENT - " + message);
} catch (IOException e) {
chatWindow.append("\n Smth is wrong sending message");
}
}
private void showMessage(final String m) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
chatWindow.append(m);
}
});
}
private void ableToType(final boolean tof) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
userText.setEditable(tof);
}
});
}
}
Android Client code:
public class MainActivity extends ActionBarActivity {
TextView text;
Socket socket;
DataInputStream is;
DataOutputStream os;
public final String TAG = "CLIENT";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView) findViewById(R.id.text);
ConnectThread thread = new ConnectThread();
thread.execute();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public class ConnectThread extends AsyncTask<String, String, String> {
public ConnectThread() {
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
Log.i(TAG,"Do in background");
return connect();
}
public String connect() {
try {
Log.i(TAG," creating socket");
socket = new Socket("192.168.1.10", 9000);
Log.i(TAG," socket created");
os = new DataOutputStream(socket.getOutputStream());
is = new DataInputStream(socket.getInputStream());
Log.i(TAG," Streams are set");
Log.i(TAG,"::"+is.readUTF().toString());
text.setText(is.readLine().toString());
return is.readLine().toString();
} catch (UnknownHostException e) {
e.printStackTrace();
Log.d("fail", e.toString());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.d("fail", e.toString());
}
return "nothing";
}
}
}

I have solved my problem. Im sending messages from my java server to android trough a socket, and android is always listening. Here is my code:
Java :
public class Server extends JFrame {
private JTextField userText;
private JTextArea chatWindow;
private ObjectOutputStream output;
private ObjectInputStream input;
// private DataInputStream input;
private Socket connection;
ServerSocket server;
public Server() {
super("GUI");
userText = new JTextField();
userText.setEditable(false);
userText.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
sendMessage(e.getActionCommand());
userText.setText("");
}
});
add(userText, BorderLayout.NORTH);
chatWindow = new JTextArea();
add(new JScrollPane(chatWindow), BorderLayout.CENTER);
setSize(300, 150);
setVisible(true);
}
// connect to server
public void startRunning() {
try {
server = new ServerSocket(9000, 100);
while (true) {
try {
waitForConnection();
setupStreams();
whileChatting();
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (EOFException e) {
showMessage("\n Connection lost");
} catch (IOException e) {
e.printStackTrace();
} finally {
closeCrap();
}
}
// connect to server
private void waitForConnection() throws IOException {
showMessage(" \nWaiting for connection \n");
connection = server.accept();
showMessage(" now connected to "
+ connection.getInetAddress().getHostName());
}
private void setupStreams() throws IOException {
showMessage("\n Setting up streams \n");
output = new ObjectOutputStream(connection.getOutputStream());
output.flush();
// input = new DataInputStream(connection.getInputStream());
input = new ObjectInputStream(connection.getInputStream());
showMessage(" Streams are good \n");
}
private void whileChatting() throws IOException {
ableToType(true);
String message = "You are now connected ";
sendMessage(message);
do {// have conversation
try {
message = (String) input.readObject();
// message = (String) input.readLine();
showMessage("\n" + message);
} catch (ClassNotFoundException e) {
showMessage("Dont know that object type ");
// TODO: handle exception
}
} while (!message.equals("server - end"));
}
// close everything
private void closeCrap() {
showMessage("\n Closing..");
ableToType(false);
try {
output.close();
input.close();
connection.close();
} catch (IOException e) {
e.printStackTrace();
}
}
// send message to server
private void sendMessage(String message) {
try {
output.writeUTF("CLIENT - " + message);
output.flush();
showMessage("\n" + "CLIENT - " + message);
} catch (IOException e) {
chatWindow.append("\n Smth is wrong sending message");
}
}
private void showMessage(final String m) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
chatWindow.append(m);
}
});
}
private void ableToType(final boolean tof) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
userText.setEditable(tof);
}
});
}
}
And android :
public class MainActivity extends ActionBarActivity {
TextView text;
Socket socket;
DataInputStream is;
ObjectOutputStream os;
public final String TAG = "CLIENT";
Handler handler;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (TextView) findViewById(R.id.text);
handler = new Handler();
Thread x = new Thread(new ClientThread());
x.start();
handler = new Handler();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
//
public class ClientThread implements Runnable {
public ClientThread() {
// TODO Auto-generated constructor stub
}
#Override
public void run() {
// TODO Auto-generated method stub
try {
while (true) {
socket = new Socket("192.168.1.10", 9000);
handler.post(new Runnable() {
#Override
public void run() {
text.setText("Connected.");
try {
os = new ObjectOutputStream(socket.getOutputStream());
} catch (Exception e) {
text.setText("Output stream. smth wrong");
Log.i(TAG, "Output stream. smth wrong");
}
}
});
try {
ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
String line = null;
while ((line = in.readUTF()) != null) {
Log.d("ServerActivity", line);
final String mesg = line;
handler.post(new Runnable() {
#Override
public void run() {
// DO WHATEVER YOU WANT TO THE FRONT END
// THIS IS WHERE YOU CAN BE CREATIVE
text.append(mesg + "\n");
}
});
}
break;
} catch (Exception e) {
handler.post(new Runnable() {
#Override
public void run() {
text.setText("Oops. Connection interrupted. Please reconnect your phones.");
}
});
e.printStackTrace();
}
}
} catch (Exception x) {
}
}
}
}

Related

Android:How to make all activity can use socket connections

I had to establish a socket in ActivityA in normal and ready to send data,
but now I want to also be able to use the same socket connection to transmit the data in ActivityB.I have looked for information on the Internet, it seems can use the singleton.I studied for a few days, I still don't know how to start, even find some examples of exercises too, but still do not know how to use my original program.
I want to first establish between ActivityA and SERVER connection, and to pass a value to the SERVER, then press the button to switch to ActivityB, and also transmit values to SERVER
Give me some advice or teaching sites can be, so that I can continue to study it, thank you very much
Establish socket methods:
public class MainActivity extends Activity {
Button Btn_Wifi,Btn_Power,Btn_Flame;
Boolean connected=false;
Boolean powerstatus=false;
DataOutputStream dataOutputStream = null;
DataInputStream dataInputStream = null ;
Socket socket = null;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainView();
setListensers();
setButtonStatus();
}
private void mainView(){
Btn_Wifi = (Button) findViewById(R.id.Btn_Wifi);
Btn_Power = (Button) findViewById(R.id.Btn_Power);
Btn_Flame = (Button) findViewById(R.id.Btn_Flame);
}
private void setListensers(){
Btn_Wifi.setOnClickListener(BtnWifiOnClickListener);
Btn_Power.setOnClickListener(BtnPowerOnClickListener);
Btn_Flame.setOnClickListener(BtnFlameOnClickListener);
}
private void setButtonStatus(){
Btn_Power.setEnabled(false);
Btn_Flame.setEnabled(false);
}
Button.OnClickListener BtnWifiOnClickListener = new Button.OnClickListener(){
#Override
public void onClick(View view) {
if(!connected){
try {
socket = new Socket("IP", PORT);
dataOutputStream = new DataOutputStream(socket.getOutputStream());//and stream
changeConnectionStatus(true);//change the connection status
}catch (UnknownHostException e) {
changeConnectionStatus(false);
}catch (IOException e) {
changeConnectionStatus(false);
}
}else{
try {//try to close the socket
socket.close();
changeConnectionStatus(false);//change the connection status
} catch (UnknownHostException e) {//catch and
changeConnectionStatus(false);
} catch (IOException e) {//catch and
changeConnectionStatus(false);
}
}
}
};
Button.OnClickListener BtnPowerOnClickListener = new Button.OnClickListener(){
#Override
public void onClick(View view) {
if(!powerstatus){
try {
byte[] pon ={(byte) 0x10,(byte) 0x10};
dataOutputStream.write(pon);
dataOutputStream.flush();
PowerStatus(true);
}catch(Exception obj){
PowerStatus(false);
}
}else{
try {
byte[] poff ={(byte) 0x11,(byte) 0x11};
dataOutputStream.write(poff); //writeBytes(String str)
dataOutputStream.flush();
PowerStatus(false);
}catch(Exception obj){
PowerStatus(true);
}
PowerStatus(false);
}
}
};
Button.OnClickListener BtnFlameOnClickListener = new Button.OnClickListener(){
#Override
public void onClick(View view) {
Intent intent = new Intent();
intent.setClass(MainActivity.this, FlameActivity.class);
startActivity(intent);
}
};
public void changeConnectionStatus(Boolean isConnected) {
connected=isConnected;//change variable
if(isConnected){//if connection established
Btn_Wifi.setText("CONNECTED");
Btn_Power.setEnabled(true);
}else{
Btn_Wifi.setText("NOT WIFI");
Btn_Power.setText("POWER OFF");
Btn_Power.setEnabled(false);
PowerStatus(false);
}
}
public void PowerStatus(Boolean isPowerOn) {
powerstatus=isPowerOn;//change variable
if(isPowerOn){//if connection established
Btn_Power.setText("POWER ON");
Btn_Flame.setText("SET FLAME");
Btn_Flame.setEnabled(true);
}else{
Btn_Power.setText("POWER OFF");
Btn_Flame.setText("CANT SET FLAME");
Btn_Flame.setEnabled(false);
}
}
}

You can certainly use it by declaring,i.e: in MainActivity which creates socket connection,static YourSocketClass objSocket // which creates connection and to use it in another Activity just called it as follow i.e:MainActivity.objSocket.yourMethod(any_param). by declaring static you can access it.
public static CommunicationClient objCommunicationClient;
public boolean setConnection(final String ipAddress, final Context context,
final boolean isFromSearch) {
class EstablishConnection extends AsyncTask<Void, Void, Boolean> {
ProgressDialog objDialog;
#Override
protected void onPreExecute() {
objDialog = new ProgressDialog(context);
objDialog.setMessage(context.getResources().getString(
R.string.strConnecting));
objDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
objDialog.show();
objDialog.setCancelable(false);
objDialog.setCanceledOnTouchOutside(false);
super.onPreExecute();
}
#Override
protected Boolean doInBackground(Void... params) {
boolean isConnected = false;
boolean isValid = false;
StrictMode.setThreadPolicy(policy);
objCommunicationClient = new CommunicationClient(ipAddress);
isSocketInitiated = objCommunicationClient.initSocket();
WifiManager wifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
WifiInfo info = wifiManager.getConnectionInfo();
CommonUtils.SSID = info.getSSID();
if (!isSocketInitiated) {
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(
getApplicationContext(),
getResources().getString(
R.string.strCantConnect),
Toast.LENGTH_LONG).show();
}
});
} else {
isConnected = true;
if (!isFromSearch) {
CommonUtils.IP = ipAddress;
try {
objCommunicationClient.sendRequest(context,
"<APP_SPECIFIC>");
} catch (Exception e) {
e.printStackTrace();
}
} else {
isValid = isFromSearch;
}
if (isValid) {
final Intent objIntentToGraph = new Intent(context,
GraphDataActivity.class);
objIntentToGraph
.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
runOnUiThread(new Runnable() {
#Override
public void run() {
startActivity(objIntentToGraph);
overridePendingTransition(
R.anim.slide_in_right,
R.anim.slide_out_left);
finish();
}
});
}
}
return isConnected;
}
#Override
protected void onPostExecute(Boolean result) {
try {
objDialog.cancel();
} catch (Exception err) {
err.printStackTrace();
}
super.onPostExecute(result);
}
}
boolean status = false;
try {
status = new EstablishConnection().execute().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
return status;
}
}
// and in my other Activity i called it as
MainActivity_HomePage.objCommunicationClient.sendRequest(
context, CommonUtils.STOP_COMMAND); //send request is method which send message to server.

passing data from BroadcastReceiver to class that extends runnable

My goal is to create a method that gets the data from broadcast receiver and sends it trough a socket. I know how to send it, but how can i get a data from BroadcastReceiver ? I want to receive data in this class:
public class ClientThread implements Runnable{
Socket socket;
public final String TAG = "CLIENT";
ObjectOutputStream os;
TextView text;
Handler handler;
AppHelper helperClass;
Activity mActivity;
Context mContext;
public ClientThread(Activity mActivity,TextView text,Context context) {
// TODO Auto-generated constructor stub
this.text=text;
this.mContext=context;;
helperClass = new AppHelper(context, mActivity);
handler = new Handler();
}
#Override
public void run() {
// TODO Auto-generated method stub
try {
while (true) {
socket = new Socket("192.168.1.10", 9000);
handler.post(new Runnable() {
#Override
public void run() {
text.setText("Connected.");
try {
os = new ObjectOutputStream(socket
.getOutputStream());
} catch (Exception e) {
text.setText("Output stream. smth wrong");
Log.i(TAG, "Output stream. smth wrong");
}
}
});
try {
ObjectInputStream in = new ObjectInputStream(
socket.getInputStream());
String line = null;
while ((line = in.readUTF().toString()) != null) {
Log.d("ServerActivity", line);
final String mesg = line;
handler.post(new Runnable() {
#Override
public void run() {
if (mesg.contains("getcontacts")) {
try {
sendContacts();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else if (mesg.contains("getmsg")) {
getMessages();
} else if (mesg.contains("sendmsg")) {
sendMessage(mesg);
} else {
// DO WHATEVER YOU WANT TO THE FRONT END
// THIS IS WHERE YOU CAN BE CREATIVE
text.append(mesg + "\n");
}
}
});
}
break;
} catch (Exception e) {
handler.post(new Runnable() {
#Override
public void run() {
text.setText("Oops. Connection interrupted. Please reconnect your phones.");
}
});
e.printStackTrace();
}
}
} catch (Exception x) {
}
}
public void receivedMessage(String sender, String message) {
}
private void sendMessage(String s) {
String[] x = s.split(" ");
int lenght = x.length;
String message = x[2];
for (int i = 3; i < x.length; i++) {
message = message + " " + x[i];
}
System.out.println(message);
SmsManager smsManager = SmsManager.getDefault();
System.out.println("sending message");
smsManager.sendTextMessage(x[1], null, message, null, null);
System.out.println("message send");
}
private void sendContacts() throws IOException {
final List<Person> list = helperClass.getContacts();
final String json = new Gson().toJson(list);
Log.i(TAG, "lenght " + json.length());
handler.post(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
try {
os.writeObject(json);
os.flush();
} catch (IOException e) {
// TODO Auto-generated catch block
Log.e(TAG, "Sending Contact list has failed");
e.printStackTrace();
}
}
});
}
private void getMessages() {
// TODO Auto-generated method stub
ProgressTask task = new ProgressTask();
ProgressTask.execute(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
try {
List<Sms> sms = helperClass.getAllSms();
final String json = new Gson().toJson(sms);
os.writeObject(json);
os.flush();
System.out.println("List of messages send");
} catch (Exception e) {
Log.e(TAG, "Sending Contact list has failed");
}
}
});
}
}

You may use an interface as listener to this runnable.
Create a Listener interface
Declare Interface Variable in Application Context.
Instantiate and implement interface in Runnable class.
In BroadcastReciever, call method of that interface.
Ex:
Class A extends Application{
public Listener listener;
}`
interface Listener{
public void yourmethod();
}
In Your clientthread method instantiate listener as follows:
((A)context.getApplication()).listener = new Listener(){
#override
public void yourmethod(){
// your implementation goes here
}
}
In your broadcast reciever.
((A)context.getApplication()).listener.yourmethod();

UDP with android

why UDP Android just once send [Please Help]
name class MainActivity
public class MainActivity extends Activity implements
android.view.View.OnClickListener {
public static final String SERVERIP = "192.168.5.255";
public static final int SERVERPORT = 4444;
public TextView text1;
public EditText input;
public Button btn;
public boolean start;
public Handler Handler;
conntection with pc
this method on create
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text1 = (TextView) findViewById(R.id.textView1);
input = (EditText) findViewById(R.id.editText1);
btn = (Button) findViewById(R.id.button1);
btn.setOnClickListener(this);
start = false;
new Thread(new Server()).start();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
}
new Thread(new Client()).start();
Handler = new Handler() {
#Override
public void handleMessage(Message msg) {
String text = (String) msg.obj;
text1.append(text);
}
};
}
this class Client
#SuppressLint("NewApi")
public class Client implements Runnable {
#Override
public void run() {
while (start == false) {
}
try {
Thread.sleep(500);
} catch (InterruptedException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
InetAddress serverAddr = InetAddress.getByName(SERVERIP);
updatetrack("Client: Start connecting\n");
DatagramSocket socket = new DatagramSocket();
byte[] buf;
if (!input.getText().toString().isEmpty()) {
buf = input.getText().toString().getBytes();
} else {
buf = ("Default message").getBytes();
}
DatagramPacket packet = new DatagramPacket(buf, buf.length,
serverAddr, SERVERPORT);
updatetrack("Client: Sending ‘" + new String(buf) + "’\n");
socket.send(packet);
updatetrack("Client: Message sent\n");
updatetrack("Client: Succeed!\n");
} catch (Exception e) {
updatetrack("Client: Error!\n");
}
}
}
this class Client
public class Server implements Runnable {
#Override
public void run() {
while (start = false) {
try {
InetAddress serverAddress = InetAddress.getByName(SERVERIP);
updatetrack("nServer: Start connectingn");
DatagramSocket socket = new DatagramSocket(SERVERPORT,
serverAddress);
byte[] buffer = new byte[17];
DatagramPacket packet = new DatagramPacket(buffer,
buffer.length);
updatetrack("Server: Receivingn");
socket.receive(packet);
updatetrack("Server: Message received:"
+ new String(packet.getData()) + "'n");
updatetrack("Server : Succed!n");
} catch (Exception e) {
updatetrack("Server: Error!n" + e.getMessage());
}
}
}
}
public void updatetrack(String s) {
Message msg = new Message();
String textTochange = s;
msg.obj = textTochange;
Handler.sendMessage(msg);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (v.getId() == R.id.button1)
start = true;
}
}
if i make my class server with
while (true){
application is error
help me please ? why just once send message Thanks before

For Client class, you have nothing in the loop:
while (start == false) {
}
And then outside of it, you call send only once -- that is why it is sending only once.
socket.send(packet);
If you want to call send continuously, then one way to do is to keep it in a loop. Of course, you would need to terminate the loop once the task is done but that would be driven by your application logic.

Android BluetoothSocket immediately disconnects after connecting

I'm pretty new to Android. Right now I'm trying to make a two-player Pong game using the Bluetooth API. I've more or less tried to copy the BluetoothChat tutorial on the Android website, but I still get an error where the socket immediately disconnects after I switch over to the ConnectedThread. Would anyone have any idea why this is?
I have each of the three types of threads as a private class on a screen of a menu. ConnectThread is split into reading and writing, and is placed inside the screen of the game.
public abstract class FindScreen extends EngineView {
private GUIFactory guiFact;
private TextButton backButton;
private ScrollingList buttonList;
public ConnectThread connectThread;
private BluetoothAdapter adapter;
public FindScreen(Context c, AndroidView aView) {
super(c, aView, 1);
adapter = BluetoothAdapter.getDefaultAdapter();
guiFact = new GUIFactory(new Vector2d(EngineConstants.CENTER_X,
EngineConstants.CENTER_Y), 8, 8, EngineConstants.VIRTUAL_W,
EngineConstants.VIRTUAL_H, EngineConstants.VIRTUAL_W / 32);
GUITask backTask = new GUITask() {
public void execute() {
goBack();
}
};
backButton = guiFact.newGradientTextButton(1, 6, 7, 7, backTask, "Back");
this.add(backButton, 0);
buttonList = guiFact.newScrollingList(1,1,7,6);
this.add(buttonList, 0);
}
#Override
public boolean onTouchEvent(MotionEvent e) {
backButton.executeIfContained(e.getX(), e.getY());
buttonList.executeIfContained(e.getX(), e.getY());
return true;
}
public void onIn() {
// Register for broadcasts when a device is discovered
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
context.registerReceiver(receiver, filter);
// Register for broadcasts when discovery has finished
filter = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
context.registerReceiver(receiver, filter);
buttonList.clearButtons();
if(!adapter.startDiscovery()) { // if discovery doesn't start successfully, leave the screen
goBack();
}
}
public void onOut() {
if (adapter.isDiscovering()) {
adapter.cancelDiscovery();
}
context.unregisterReceiver(receiver);
if (connectThread != null) {
connectThread.cancel();
}
}
/**
* Return to the previous screen, the menu screen
*/
public abstract void goBack();
/**
* Do something after we've connected
* #param socket
*/
public abstract void connected(BluetoothSocket socket);
/**
* Broadcast receiver;
* Listens for discovered devices
* When discovery is finished, changes the list of discovered devices
* When discoverability is changed, changes text
*/
private final BroadcastReceiver receiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
BluetoothDevice device = intent
.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// if (device.getBondState() != BluetoothDevice.BOND_BONDED) {
buttonList.addButton(device.getName(), new ConnectTask(device.getAddress()));
// }
// doDiscovery();
}
}
};
private class ConnectTask extends GUITask {
private String address;
public ConnectTask(String addr) {
address = addr;
}
#Override
public void execute() {
BluetoothDevice device = adapter.getRemoteDevice(address);
if (connectThread != null) {
connectThread.cancel();
}
connectThread = new ConnectThread(device);
connectThread.start();
}
}
private class ConnectThread extends Thread {
private final BluetoothSocket socket;
private final BluetoothDevice device;
public ConnectThread(BluetoothDevice dev) {
// Use a temporary object that is later assigned to mmSocket,
// because mmSocket is final
BluetoothSocket tmp = null;
device = dev;
// Get a BluetoothSocket to connect with the given BluetoothDevice
try {
// MY_UUID is the app's UUID string, also used by the server code
tmp = device.createRfcommSocketToServiceRecord(EngineConstants.MY_UUID);
} catch (IOException e) { }
socket = tmp;
}
public void run() {
// Cancel discovery because it will slow down the connection
if (adapter.isDiscovering()) {
adapter.cancelDiscovery();
}
try {
// Connect the device through the socket. This will block
// until it succeeds or throws an exception
socket.connect();
} catch (IOException connectException) {
// Unable to connect; close the socket and get out
try {
socket.close();
} catch (IOException closeException) { }
return;
}
// Do work to manage the connection (in a separate thread)
connected(socket);
}
/** Will cancel an in-progress connection, and close the socket */
public void cancel() {
try {
socket.close();
} catch (IOException e) { }
}
}
public abstract class HostScreen extends EngineView {
private GUIFactory guiFact;
private TextButton backButton;
private TextLabel waitText;
private BluetoothAdapter adapter;
public AcceptThread acceptThread;
private static final int DISCOVERY_LENGTH = 300;
public HostScreen(Context c, AndroidView aView) {
super(c, aView, 1);
adapter = BluetoothAdapter.getDefaultAdapter();
guiFact = new GUIFactory(new Vector2d(EngineConstants.CENTER_X,
EngineConstants.CENTER_Y), 8, 8, EngineConstants.VIRTUAL_W,
EngineConstants.VIRTUAL_H, EngineConstants.VIRTUAL_W / 32);
GUITask backTask = new GUITask() {
public void execute() {
goBack();
}
};
backButton = guiFact.newGradientTextButton(1, 6, 7, 7, backTask, "Back");
this.add(backButton, 0);
waitText = guiFact.newLabel(2, 3, 6, 4, Color.WHITE, "...");
this.add(waitText, 0);
}
public void onIn() {
if (adapter.getScanMode() != BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, DISCOVERY_LENGTH);
((Activity) context).startActivityForResult(discoverableIntent, EngineConstants.REQUEST_DISCOVERABLE);
}
if (!adapter.isEnabled()) {
Intent enableIntent = new Intent(
BluetoothAdapter.ACTION_REQUEST_ENABLE);
context.startActivity(enableIntent);
}
}
public void onOut() {
if (acceptThread != null) {
acceptThread.cancel();
}
}
public void discoverableAccepted() {
if (acceptThread != null) {
acceptThread.cancel();
}
acceptThread = new AcceptThread();
acceptThread.start();
}
public void discoverableDeclined() {
goBack();
}
/**
* Do something after we've connected
* #param socket
*/
public abstract void connected(BluetoothSocket socket);
#Override
public boolean onTouchEvent(MotionEvent e) {
backButton.executeIfContained(e.getX(), e.getY());
return true;
}
/**
* Return to the previous screen, the menu screen
*/
public abstract void goBack();
private class AcceptThread extends Thread {
private final BluetoothServerSocket serverSocket;
public AcceptThread() {
// Use a temporary object that is later assigned to mmServerSocket,
// because mmServerSocket is final
BluetoothServerSocket tmp = null;
try {
// MY_UUID is the app's UUID string, also used by the client code
tmp = adapter.listenUsingRfcommWithServiceRecord(EngineConstants.NAME, EngineConstants.MY_UUID);
} catch (IOException e) { }
serverSocket = tmp;
}
public void run() {
BluetoothSocket socket = null;
// Keep listening until exception occurs or a socket is returned
while (true) {
try {
socket = serverSocket.accept();
} catch (IOException e) {
break;
}
// If a connection was accepted
if (socket != null) {
// Do work to manage the connection (in a separate thread)
connected(socket);
try {
serverSocket.close();
} catch (IOException e) {
android.util.Log.d("Accept thread", "Could not close serverSocket");
}
break;
}
}
}
/** Will cancel the listening socket, and cause the thread to finish */
public void cancel() {
try {
serverSocket.close();
} catch (IOException e) { }
}
}
}
public class GameScreen extends EngineView {
public ConnectedThread connectedThread;
public ConnectedWriteThread writeThread;
private PacketHandler handler;
private final static int N_LAYERS = 4;
// layer 0 = walls
// layer 1 = puck
// layer 2 = paddles
// layer 3 = GUI
public Paddle enemyPaddle, playerPaddle;
public Puck puck;
private GUIFactory guiFact;
private TextLabel playerLabel, enemyLabel;
public int playerScore = 0, enemyScore = 0;
private boolean isHeld;
private float startX, startTouchX, moveToX;
private final static float MIN_X = Paddle.RADIUS, MAX_X = EngineConstants.VIRTUAL_W - MIN_X;
public float myPaddlePrevPosX;
public boolean enemyScoreChanged = false;
private final static long PACKET_RATE = 200;
private long packetTime = 0;
public GameScreen(Context c, final AndroidView aView) {
super(c, aView, N_LAYERS);
enemyPaddle = new Paddle(new Vector2d(EngineConstants.CENTER_X, EngineConstants.VIRTUAL_H/8f), 255, 255, 100, 100);
playerPaddle = new Paddle(new Vector2d(EngineConstants.CENTER_X, EngineConstants.VIRTUAL_H*7f/8f), 255, 100, 255, 100);
puck = new Puck();
this.add(enemyPaddle, 2);
this.add(playerPaddle, 2);
this.add(puck, 1);
guiFact = new GUIFactory(new Vector2d(EngineConstants.CENTER_X, EngineConstants.CENTER_Y), 8, 10, EngineConstants.VIRTUAL_W, EngineConstants.VIRTUAL_H, 0);
playerLabel = guiFact.newLabel(2, 4, 3, 5, Color.rgb(100, 150, 100), "0");
enemyLabel = guiFact.newLabel(7, 3, 8, 4, Color.rgb(150, 100, 100), "0");
this.add(playerLabel, 3);
this.add(enemyLabel, 3);
this.constraints.add(new BoxConstraint(puck, false, false, 0 + Puck.RADIUS));
this.constraints.add(new BoxConstraint(puck, false, true, EngineConstants.VIRTUAL_W - Puck.RADIUS));
myPaddlePrevPosX = playerPaddle.pos.x;
}
public void onOut() {
if (connectedThread != null) {
connectedThread.cancel();
}
if (writeThread != null) {
writeThread.cancel();
}
}
public void update(long interval) {
super.update(interval);
EngineFunctions.collide(playerPaddle, puck);
EngineFunctions.collide(enemyPaddle, puck);
if (puck.pos.y < 0) {
score(true);
} else if (puck.pos.y > EngineConstants.VIRTUAL_H) {
score(false);
}
packetTime += interval;
if (packetTime > PACKET_RATE) {
// android.util.Log.d("fillQueue", "called");
packetTime = 0;
writeThread.fillQueue();
}
}
private void score(boolean isPlayer) {
if (isPlayer) {
playerScore++;
playerLabel.setText(String.valueOf(playerScore));
} else {
enemyScore++;
enemyLabel.setText(String.valueOf(enemyScore));
enemyScoreChanged = true;
}
puck.pos.x = EngineConstants.CENTER_X;
puck.pos.y = EngineConstants.CENTER_Y;
puck.prevPos.x = EngineConstants.CENTER_X;
puck.prevPos.y = EngineConstants.CENTER_Y;
}
#Override
public boolean onTouchEvent(MotionEvent e) {
switch(e.getAction()) {
case MotionEvent.ACTION_DOWN:
if (playerPaddle.touching(e.getX(), e.getY())) {
isHeld = true;
startX = playerPaddle.pos.x;
startTouchX = e.getX();
}
break;
case MotionEvent.ACTION_MOVE:
if (isHeld) {
myPaddlePrevPosX = playerPaddle.pos.x;
moveToX = startX + (e.getX() - startTouchX);
if (moveToX < MIN_X) {
moveToX = MIN_X;
} else if (moveToX > MAX_X) {
moveToX = MAX_X;
}
playerPaddle.pos.x = moveToX;
playerPaddle.prevPos.x = moveToX;
}
break;
case MotionEvent.ACTION_UP:
isHeld = false;
break;
}
return true;
}
public void startNewConnectedThread(BluetoothSocket soc, boolean isServer) {
if (connectedThread != null) {
connectedThread.cancel();
}
connectedThread = new ConnectedThread(soc, handler);
connectedThread.start();
if (writeThread != null) {
writeThread.cancel();
}
writeThread = new ConnectedWriteThread(soc, handler, isServer);
writeThread.start();
}
public void setHandler(PacketHandler h) {
handler = h;
}
public class ConnectedThread extends Thread {
private final BluetoothSocket socket;
private final InputStream inStream;
private final BufferedReader in;
private PacketHandler handler;
public ConnectedThread(BluetoothSocket soc, PacketHandler pHandler) {
socket = soc;
handler = pHandler;
InputStream tmpIn = null;
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpIn = socket.getInputStream();
} catch (IOException e) {
}
inStream = tmpIn;
in = new BufferedReader(new InputStreamReader(inStream));
}
public void run() {
/*
// Keep listening to the InputStream until an exception occurs
android.util.Log.d("connectedThread", "started");
String str;
try {
inStream.read();
inStream.read();
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
android.util.Log.d("connectedThread", "normal read is fine");
while (true) {
try {
// Read from the InputStream
str = in.readLine();
byte type = Byte.valueOf(str);
android.util.Log.d("connectedThread", "read");
handler.handlePacket(in, type);
} catch (IOException e) {
break;
}
}*/
for (int i = 0; i < 20; i++) {
try {
String str = in.readLine();
android.util.Log.d("read", str + " ");
} catch (IOException e) {
// TODO Auto-generated catch block
android.util.Log.d("io exception", e.getMessage() + " " + e.getLocalizedMessage() + " " + e.getCause());
}
}
while (true) {
}
}
/* Call this from the main Activity to shutdown the connection */
public void cancel() {
try {
socket.close();
} catch (IOException e) { }
}
}
public class ConnectedWriteThread extends Thread {
public ConcurrentLinkedQueue<String> que;
private final BluetoothSocket socket;
private final OutputStream outStream;
private final BufferedWriter out;
private PacketHandler handler;
private boolean isServ;
public ConnectedWriteThread(BluetoothSocket soc, PacketHandler pHandler, boolean isServer) {
socket = soc;
handler = pHandler;
isServ = isServer;
OutputStream tmpOut = null;
que = new ConcurrentLinkedQueue<String>();
// Get the input and output streams, using temp objects because
// member streams are final
try {
tmpOut = socket.getOutputStream();
} catch (IOException e) { }
outStream = tmpOut;
out = new BufferedWriter(new OutputStreamWriter(outStream));
}
public void run() {
// Keep listening to the InputStream until an exception occurs
android.util.Log.d("connectedThread", "started");
/*
try {
if (isServ) {
out.write(String.valueOf(EngineConstants.PACKET_SYNC) + '\n');
out.write(String.valueOf(0) + '\n');
}
} catch (IOException e1) {
android.util.Log.d("connectedThread", "io exception " + e1.getMessage() + " " + e1.getLocalizedMessage() + " " + e1.getCause());
}
//android.util.Log.d("connectedThread", "sent initial packet");
while (true) {
if (!que.isEmpty()) {
try {
out.write(que.poll());
out.flush();
// android.util.Log.d("connectedThread", "sent packet");
} catch (IOException e) {
android.util.Log.d("write thread", "io exception " + e.getMessage());
}
}
}*/
try {
outStream.write(3);
out.write("343567\n");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
while (true) {
}
}
public void fillQueue() {
// android.util.Log.d("fillQueue", "in method");
handler.queuePacket(que);
}
/* Call this from the main Activity to send data to the remote device */
public void write(String str) {
try {
out.write(str);
} catch (IOException e) { }
}
/* Call this from the main Activity to shutdown the connection */
public void cancel() {
try {
socket.close();
} catch (IOException e) { }
}
}

Try to use reflection:
try {
BluetoothDevice mDevice = mBluetoothAdapter.getRemoteDevice("MAC of remote device");
Method m = mDevice.getClass().getMethod("createRfcommSocket",
new Class[] { int.class });
mSocket = (BluetoothSocket) m.invoke(mDevice, Integer.valueOf(1));
mSocket.connect();
} catch (NoSuchMethodException e) {
} catch (SecurityException e) {
} catch (IllegalArgumentException e) {
} catch (IllegalAccessException e) {
} catch (InvocationTargetException e) {
} catch (Exception e) {}
And after some time in your thread
mInStream = mSocket.getInputStream();
mOutStream = mSocket.getOutputStream();
mInStream is InputStream() and mOutStream is OutputStream().
I came across this problem when used bluetooth connection on HTC device.

java.lang.NullPointerException at android.content.ContextWrapper.getPackageManager

I am getting this error
java.lang.NullPointerException at android.content.ContextWrapper.getPackageManager
when am trying to get list of all installed applications on the device.
I have a server that starts when my application is started, and the client pings the server and asks to get a list of installed applications. The Server then asks the getPackageManager() and gets all the installed applications.
But the getPackageManager throws a NullPointerException.
The Server is written in a java and is started from my android application.
Could someone please tell me what am missing and why I am getting this error?
Please find the code below
public class ApplicationRecognition extends Activity {
// android.os.Debug.waitForDebugger();
Button buttonStart, buttonStop;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
buttonStart = (Button) findViewById(R.id.buttonStart);
buttonStop = (Button) findViewById(R.id.buttonStop);
final SecurityModuleServer server = new SecurityModuleServer(5902);
server.start();
Toast.makeText(this, "Application Server is started", Toast.LENGTH_SHORT).show();
buttonStart.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
startService(new Intent(getBaseContext(), AppReconService.class));
}});
buttonStop.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
stopService(new Intent(getBaseContext(), AppReconService.class));
}});
}
public String[] getInstalledApplications()
{
String[] appname =new String[10];
Intent mainIntent = new Intent(Intent.ACTION_MAIN,null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
PackageManager manager = getPackageManager();
List<ResolveInfo> pkgAppsList = manager.queryIntentActivities(mainIntent, 0);
appname = new String[pkgAppsList.size()];
for(int i=0;i<pkgAppsList.size();i++)
{
appname[i]=pkgAppsList.get(i).activityInfo.packageName;
}
return appname;
}
}
the server side code
public class SecurityModuleServer implements Observer,Runnable
{
private int numberOfConnectedClient;
private Thread serverThread;
private ServerSocket serverSocket;
private volatile boolean isServerRunning;
public SecurityModuleServer(final int port)
{
numberOfConnectedClient = 0;
try
{
serverSocket = new ServerSocket(port);
} catch (IOException e) {
e.printStackTrace();
}
}
public void run()
{
System.out.println("SecurityModuleServer>> server thread started."); //$NON-NLS-1$
while(isServerRunning)
{
numberOfConnectedClient++;
try
{
SecurityModuleClientThread client = new SecurityModuleClientThread(serverSocket.accept(), numberOfConnectedClient);
client.addObserver(this);
client.start();
}
catch (IOException e)
{
e.printStackTrace();
}
}
System.out.println("SecurityModuleServer>> server thread stopped."); //$NON-NLS-1$
}
synchronized public void start()
{
serverThread = new Thread(this);
isServerRunning = true;
serverThread.start();
}
synchronized public void stop()
{
isServerRunning = false;
}
public boolean isRunning()
{
return isServerRunning;
}
public static void main(String[] args)
{
SecurityModuleServer server = new SecurityModuleServer(5903);
server.start();
}
public void update(Observable o, Object arg)
{
numberOfConnectedClient--;
}
}
the client side code
public SecurityModuleClientThread(Socket socket, int numberOfClient)
{
clientSocket = socket;
numberOfConnectedClient = numberOfClient;
try
{
printOut = new PrintStream(clientSocket.getOutputStream());
readerIn = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
clientThread = new Thread(this);
}
catch (IOException e)
{
e.printStackTrace();
}
}
public void run()
{
Looper.prepare();
String input = ""; //$NON-NLS-1$
System.out.println("SecurityModuleClientThread>> thread started for client."); //$NON-NLS-1$
if (numberOfConnectedClient <= MAX_ALLOWED_CLIENTS)
{
printOut.println(CMD+Answer_Open_Connection+SEPARATOR+M002);
while(isClientRunning)
{
try
{
input = readerIn.readLine();
System.out.println("Message received>> "+input); //$NON-NLS-1$
parseInputMessage(input);
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
else
{
printOut.println(CMD+Error+SEPARATOR+M003);
stop();
}
System.out.println("SecurityModuleClientThread>> thread stopped for client."); //$NON-NLS-1$
}
private void parseInputMessage(final String input)
{
if (input.equalsIgnoreCase(CMD+Request_Close_Connection))
{
printOut.println(CMD+Answer_Close_Connection+SEPARATOR+M007);
stop();
}
else
{
String messages[] = input.split(SEPARATOR);
// Parse the command
switch(parseCommand(messages[0]))
{
case Request_Start_Application:
if(parseApplicationName(input) != null)
{
if(startAndroidApplication(parseApplicationName(input)))
{
// TODO
printOut.println(CMD+Answer_Start_Application);
startAndroidApplication(parseApplicationName(input));
}
else
{
printOut.println(CMD+Error+SEPARATOR+M004);
}
}
else
{
printOut.println(CMD+Error+SEPARATOR+M004);
}
break;
case Request_Stop_Application:
if(parseApplicationName(input) != null)
{
if (stopAndroidApplication(parseApplicationName(input)))
{
// TODO
printOut.println(CMD+Answer_Stop_Application);
}
else
{
printOut.println(CMD+Error+SEPARATOR+M004);
}
}
else
{
printOut.println(CMD+Error+SEPARATOR+M004);
}
break;
case Request_Application_Installed:
String[] appnames = new String[provideInstalledApplication().length];
appnames = provideInstalledApplication();
for(int i=0;i<appnames.length;i++)
{
printOut.println(appnames[i]);
}
break;
case Request_Application_Running:
//TODO
break;
default:
printOut.println(CMD+Error+SEPARATOR+M008);
break;
}
}
}
private int parseCommand(String cmd)
{
if (cmd.length() == 6)
{
return Integer.parseInt(cmd.substring(3, 6));
}
else
{
return 0;
}
}
private String parseApplicationName(String message)
{
if (message.length() > 6)
{
// TODO
return message.substring(6, message.length());
}
else
{
return null;
}
}
public synchronized void start()
{
isClientRunning = true;
clientThread = new Thread(this);
clientThread.start();
}
public synchronized void stop()
{
printOut.close();
try
{
readerIn.close();
clientSocket.close();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
isClientRunning = false;
setChanged();
notifyObservers();
}
}
public boolean isRunning()
{
return isClientRunning;
}
public String[] provideInstalledApplication()
{
String[] appnames = null;
ApplicationRecognition apprecon = new ApplicationRecognition();
appnames=new String[apprecon.getInstalledApplications().length];
appnames = apprecon.getInstalledApplications();
return appnames;
}
public String[] provideRunningApplication()
{
// TODO Auto-generated method stub
return null;
}
public boolean startAndroidApplication(String applicationName)
{
// TODO Auto-generated method stub
ApplicationRecognition apprecon = new ApplicationRecognition();
apprecon.startApplication(applicationName);
return false;
}
public boolean stopAndroidApplication(String applicationName)
{
// TODO Auto-generated method stub
return false;
}
}
The main part that is giving me trouble is in ApplicationRecognition class under method getInstalledApplications() in getPackageManager is null.
This method is called from the client side SecurityModuleClientThread class, provideInstalledApplication method.
Can someone please tell me where am I going wrong.

Develop Reference

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