Develop Reference

Android edittext loses and repeats texts received via TCP socket

I have a problem with a edittext in Android Studio.
Normally, log.d reports the messages received via TCP socket and
those appears in the textedit mySocketrx. When there is a fast
message burst log.d is still working fine but textedit loses and repeats
messages.
protected void onCreate(Bundle savedInstanceState) {
final EditText mySocketrx = (EditText) findViewById(R.id.Socketrx);
new Thread(new Runnable() { // Client TCP socket thread
public void run() {
try {
s = new Socket("192.168.1.161",6000);
p = new PrintStream(s.getOutputStream());
b = new BufferedReader ( new InputStreamReader( s.getInputStream() ) );
} catch(Exception ex) { }
while (true) {
try {
status = b.readLine();
Log.d("DEBUG", status);
runOnUiThread(new Runnable() {
public void run() {
mySocketrx.append(status + "\n");
}
} );
} catch(Exception ex) { }
}
}
}).start();
}

Instead of append() use the setText() method.

Android wifi: handler msg not working

I would like to ask a question about my code in Wifi client communication. I am communicating with a Raspberry Pi as server.
The architecture of my code is:
Main Activity: I have the Handler class and I launch in the OnCreat the first Thread (Thread1) that takes care of establishing the wifi connection.
public class MainActivity extends AppCompatActivity {
public int serverPort = 40000;
public String serverIP = "10.177.86.212";
public WiFiConnector wifiConnection;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editTextWE = (EditText) findViewById(R.id.editText_WE);
wifiConnection = new WiFiConnector(serverIP, serverPort);
Handler mHandler = new MyHandler();
WiFiConnector.Thread1 = new Thread(new WiFiConnector.Thread1(mHandler,true));
WiFiConnector.Thread1.start();
}
private class MyHandler extends Handler {
private byte[] bytes = null;
#Override
public void handleMessage(Message msg) {
bytes = msg.getData().getByteArray("KEY");
if(bytes!= null){
for (int i = 0; i < bytes.length; i++){
Log.d("Data received", "value " + (0xFF & bytes[i]) );
}
for (int i=0; i<bytes.length; i++) {
editTextWE.setText(editTextWE.getText()+ "Server says: " + bytes.length + " "+ (0xFF & bytes[i]) + "\n");
}
}
}
}
}
WifiConnector class: Thread1 and Thread2 are sharing the handler coming from the Main Activity. Thread1 send a command to Raspberry Pi to let it start sending data. Thread2 is dedicated to read data received from the server.
public class WiFiConnector {
static String serverIP;
static int serverPort;
public static Thread Thread1 = null;
//Constructor
public WiFiConnector(String IP, int port) {
serverIP = IP;
serverPort = port;
}
public static class Thread1 extends Thread implements Runnable {
private Handler handler1;
boolean firsttime = false;
OutputStream out ;
public Thread1(Handler handler_1, boolean firsttime) {
this.handler1 = handler_1;
this.firsttime = firsttime;
}
public void run() {
Socket socket = null;
try {
//Writing to a Socket
InetAddress serverAddress = InetAddress.getByName(serverIP);
socket = new Socket(serverAddress, serverPort);
out = new DataOutputStream(socket.getOutputStream());
if(firsttime){
//I send "B" to Raspberry to let him start sending data
out.write("B".getBytes());
this.fisrttime = false;
}
Thread2 comThread = new Thread2(socket, handler1);
new Thread(comThread).start();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public static class Thread2 implements Runnable {
public Socket clientSocket;
private Handler handler_2;
public DataInputStream in;
public byte[] bytes = new byte[13];
public Message msg;
public Thread2(Socket clientSocket, Handler handler2) {
this.clientSocket = clientSocket;
this.handler_2 = handler2;
}
public void run() {
while (!Thread.currentThread().isInterrupted()) {
try {
if (Looper.myLooper() == null) {
Looper.prepare();
}
this.in = new DataInputStream(clientSocket.getInputStream());
in.readFully(bytes);
if (in != null) {
for (int i = 0; i < bytes.length; i++){
Log.d("Data received", "valuewifi " + (0xFF & bytes[i]) );
}
msg = new Message();
Bundle b = new Bundle();
b.putByteArray("KEY", bytes);
msg.setData(b);
handler_2.sendMessage(msg);
} else {
Thread1 = new Thread(new Thread1(handler_2,false));
Thread1.start();
return;
}
} catch (IOException e) {
e.printStackTrace();
}
}
Looper.loop();
}
}
}
NOW THE PROBLEM IS:
I am receiving correctly my data (package of 13 bytes each) from Raspberry Pi, indeed:
Log.d("Data received", "valuewifi " + (0xFF & bytes[i]) );
prints correctly my values. Then I create the message to be sent to the handler in MainActivity. the Bundle contains (I have verified) the same values of the input stream received, but the message printed in the Handler of the MainActivity:
Log.d("Data received", "value " + (0xFF & bytes[i]) );
substitutes the first byte value of each message (I am trying to get 2 package each communications with the RPi) with 66 that actually is the ASCII code of "B" that I sent to start the data sending from Raspberry Pi.
PLEASE DO YOU HAVE ANY IDEA ON WHY THIS IS HAPPENING?
Many thanks for your help in advance!:)

Well, I have found that in Thread2 if I put
public byte[] bytes = new byte[13];
inside the run{..} before
in.readFully(bytes);
The exchange of message happens perfectly. Otherwise I only get in MainActivity the last package of byte received from the server.
Any suggestion on why does it happen?
Thanks!

how to link process output to textview and automatically update in realtime?

I'm not the best programmer, actually, I'm pretty bad :(
I need help with something thats driving my crazy. basically I have a tcpdump process, I want to extract the output and put it into a textview which is updated every few milliseconds, I've tried everything and just cant get it to work.
I don't get any errors and it seems to work in the background, but only displays chunks of text only after I go to the homescreen and return back into the app. however, it doesnt constantly update the textview, and sometimes hangs and crashes.
I've created a simple handler which can update the textview with plain text without problems, but then i faced major problems getting it to read the process.
Begin button
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.capture);
this.LiveTraffic = (TextView) findViewById(R.id.LiveTraffic);
this.CaptureText = (TextView) findViewById(R.id.CaptureText);
((TextView) findViewById(R.id.ipv4)).setText(getLocalIpv4Address());
((TextView) findViewById(R.id.ipv6)).setText(getLocalIpv6Address());
//Begin button
final Button startButton = (Button) findViewById(R.id.start);
startButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "Now Capturing Packets", Toast.LENGTH_LONG).show();
try {
process = Runtime.getRuntime().exec("su");
DataOutputStream os = new DataOutputStream(process.getOutputStream());
os.writeBytes("/data/local/tcpdump -q\n");
os.flush();
os.writeBytes("exit\n");
os.flush();
os.close();
inputStream = new DataInputStream(process.getInputStream());
Thread.sleep(1000);
Process process2 = Runtime.getRuntime().exec("ps tcpdump");
DataInputStream in = new DataInputStream(process2.getInputStream());
String temp = in.readLine();
temp = in.readLine();
temp = temp.replaceAll("^root *([0-9]*).*", "$1");
pid = Integer.parseInt(temp);
Log.e("MyTemp", "" + pid);
process2.destroy();
CaptureActivity.this.thisActivity.CaptureText.setText("Active");
} catch (Exception e) {
}
ListenThread thread = new ListenThread(new BufferedReader(new InputStreamReader(inputStream)));
thread.start();
}
});
}
ListenThread class
public class ListenThread extends Thread {
public ListenThread(BufferedReader reader) {
this.reader = reader;
}
private BufferedReader reader = null;
#Override
public void run() {
reader = new BufferedReader(new InputStreamReader(inputStream));
while (true) {
try {
CaptureActivity.this.thisActivity.CaptureText.setText("exec");
int a = 1;
String received = reader.readLine();
while (a == 1) {
CaptureActivity.this.thisActivity.LiveTraffic.append(received);
CaptureActivity.this.thisActivity.LiveTraffic.append("\n");
received = reader.readLine();
CaptureActivity.this.thisActivity.CaptureText.setText("in loop");
}
CaptureActivity.this.thisActivity.CaptureText.setText("out loop");
} catch (Exception e) {
Log.e("FSE", "", e);
}
}
}
}

I am not an android expert but I notice that:
you are running I/O operations in the UI thread - that will freeze your GUI until the I/O operation finishes ==> run them in a separate thread.
you update the UI from outside the UI thread in ListenThread, which can lead to unexpected results
You can read more about it in this tutorial (make sure you read the 2 examples as the first one is broken (on purpose)).
EDIT
In conclusion you should have something like this in your first piece of code:
startButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "Now Capturing Packets", Toast.LENGTH_LONG).show();
new Thread(new Runnable() {
public void run() {
try {
process = Runtime.getRuntime().exec("su");
...
CaptureActivity.this.runOnUiThread(new Runnable() {
public void run() {
CaptureActivity.this.thisActivity.CaptureText.setText("Active");
}
});
} catch (Exception e) {
}
ListenThread thread = new ListenThread(new BufferedReader(new InputStreamReader(inputStream)));
thread.start();
}
}).start();
}
});
and in the second:
while (true) {
try {
CaptureActivity.this.runOnUiThread(new Runnable() {
public void run() {
CaptureActivity.this.thisActivity.CaptureText.setText("exec");
}
});
int a = 1;
String received = reader.readLine();
while (a == 1) {
CaptureActivity.this.runOnUiThread(new Runnable() {
public void run() {
CaptureActivity.this.thisActivity.LiveTraffic.append(received);
CaptureActivity.this.thisActivity.LiveTraffic.append("\n");
CaptureActivity.this.thisActivity.CaptureText.setText("in loop");
}
});
received = reader.readLine();
}
CaptureActivity.this.runOnUiThread(new Runnable() {
public void run() {
CaptureActivity.this.thisActivity.CaptureText.setText("out loop");
}
});
} catch (Exception e) {
Log.e("FSE", "", e);
}
}
That should solve the specific UI interaction issue. But there are other logic problems in your code which go beyond this question (for example the fact that you never test if you have reached the end of the file you are reading, the fact that while(a==1) is an infinite loop because you never change the value of a etc.).

UI won't update in real time

I am trying to measure the wifi signal strength 5 times (after every second) & display it in a TextView. I simultaneously write it to external storage as well. Everything runs fine except that I am NOT able to see the results in real time. The app would run for 5 secs with a blank screen and then show up the results (which are correct btw, i.e 5 different readings after each second).
I'd want to see the results updating as soon the new value is calculated in each iteration of the for loop.
Thanks
Here is the code
public class WifiDemo extends Activity implements OnClickListener {
private static final String TAG = "WiFiDemo";
WifiManager wifi;
TextView textStatus;
Button buttonScan;
/** Called when the activity is first created. */
/*
* (non-Javadoc)
*
* #see android.app.Activity#onCreate(android.os.Bundle)
*/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Setup UI
textStatus = (TextView) findViewById(R.id.textStatus);
buttonScan = (Button) findViewById(R.id.buttonScan);
buttonScan.setOnClickListener(this);
// Setup WiFi
wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// Get WiFi status
runOnUiThread(new Runnable() {
public void run() {
try {
FileWriter fw = new FileWriter(
Environment.getExternalStorageDirectory()
+ "/bluetooth/wifi.txt");
for (int i = 0; i < 5; i++) {
WifiInfo info = wifi.getConnectionInfo();
Date d = new Date(System.currentTimeMillis());
String stat = "\n\nWiFi Status: " + info.getRssi()
+ " " + d.getHours() + ":" + d.getMinutes()
+ ":" + d.getSeconds();
textStatus.append(stat);
fw.write(stat);
fw.flush();
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
fw.close();
}
catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
textStatus.append("something wrong");
}
}
});
}
}
}

You can try to create a handler to handle UI update tasks in the main thread. Do not update UI in your thread, instead, do it by passing handler messages to make sure this job is handled in the main thread. It works fine for me. I've modified some of your code here (I removed the write file part),
public class WifiDemo extends Activity implements OnClickListener {
private static final String TAG = "WiFiDemo";
private static final int WifiDetectStart = 0;
private static final int WifiDetectStop = 1;
private String stat;
WifiManager wifi;
TextView textStatus;
Button buttonScan;
Handler handler;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Setup UI
textStatus = (TextView) findViewById(R.id.textStatus);
buttonScan = (Button) findViewById(R.id.buttonScan);
buttonScan.setOnClickListener(this);
//setup handler
handler = new Handler(){
#Override
public void handleMessage(Message msg) {
if(msg.what == WifiDetectStart)
{
textStatus.append(stat);
}
if(msg.what == WifiDetectStop)
{
Thread.currentThread().interrupt();
}
super.handleMessage(msg);
}
};
// Setup WiFi
wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// Get WiFi status
Thread myThread = new Thread(new Runnable() {
public void run() {
for (int i = 0; i < 5; i++) {
WifiInfo info = wifi.getConnectionInfo();
Date d = new Date(System.currentTimeMillis());
stat = "\n\nWiFi Status: " + info.getRssi()
+ " " + d.getHours() + ":" + d.getMinutes()
+ ":" + d.getSeconds();
Message msg = new Message();
msg.what = WifiDetectStart;
handler.sendMessage(msg);
// textStatus.append(stat);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
//finish this operation
Message msg = new Message();
msg.what = WifiDetectStop;
handler.sendMessage(msg);
}
});
myThread.start();
}
}

The problem is you're doing something right by trying to do your updating in a separate Runnable... however, your Runnable is running in the UI thread and therefore causing the UI thread to sit in the loop (including the Thread.sleep()). You're not getting your updates because you're causing the UI to wait on you.
If your processing is reasonably heavy, you might wish to break it out into a separate thread and send messages to a handler. Otherwise, it might be easiest to do something like the following (untested, but something similar):
if (Environment.MEDIA_MOUNTED.equals(state)) {
textStatus.postDelayed(new Runnable() {
public void run() {
WifiInfo info = wifi.getConnectionInfo();
Date d = new Date(System.currentTimeMillis());
String stat = "\n\nWiFi Status: " + info.getRssi()
+ " " + d.getHours() + ":" + d.getMinutes()
+ ":" + d.getSeconds();
textStatus.append(stat);
// relaunch if we're not through with our number of iterations.
// mCount is a new field.
if(mCount++ < 5) {
textStatus.postDelayed(this, 1000);
}
}
}, 1000);
}

How to change images one after the other on ImageButtons?

I'm trying to change images on buttons and turn them back to the original image, and to do it one after the other in 4 different images.
I have tried the following code, but it didn't work, the result causes only to one of the images to blink for a milisecond:
ArrayList<Integer> scenario = new ArrayList<Integer>();
...
void delayedPlay(){
// each button should be posted in 1 second spacing
int count = 1;
for (final int btnid : scenario){
// turn off
final Runnable r2 = new Runnable(){
public void run(){
imagebuttons[btnid].setImageBitmap(imagesTurnedOff.get(btnid));
}
};
// turn on and call turn off
Runnable r1 = new Runnable(){
public void run(){
imagebuttons[btnid].setImageBitmap(imagesTurnedOn.get(btnid));
imagebuttons[btnid].postDelayed(r2, 1000);
}
};
// post the above delayed
imagebuttons[btnid].postDelayed(r1, 1000 * count++);
}
}
Can anyone help me, and suggest why it doesn't working for me?

It worked for me. Are you sure that imagesTurnedOn/imagesTurnedOff are returning the correct values?
This solution leaves a lot to be desired in terms of timing -- it will be quite uneven. Perhaps something like this would work better (using an AsyncTask)
public void deplayedPlay2() {
if (mTaskHandler == null) {
mTaskHandler = new AsyncTask<Void, Void, Void>() {
#Override
public Void doInBackground(Void... params) {
long now = System.currentTimeMillis();
try {
for (final int btnid : mScenario) {
Log.d(TAG,
"ON: " + btnid + " (" + (System.currentTimeMillis() - now) + ")");
mButtons[btnid].post(new Runnable() {
public void run() {
mButtons[btnid]
.setBackgroundDrawable(GoodbyeAndroidActivity.this
.getResources()
.getDrawable(
R.drawable.on_icon));
}
});
Thread.sleep(1000);
Log.d(TAG,
"OFF: " + btnid + " (" + (System.currentTimeMillis() - now) + ")");
mButtons[btnid].post(new Runnable() {
public void run() {
mButtons[btnid]
.setBackgroundDrawable(GoodbyeAndroidActivity.this
.getResources()
.getDrawable(
R.drawable.off_icon));
}
});
}
} catch (InterruptedException ex) {
Log.d(TAG, "Interrupted.");
}
return null;
}
#Override
public void onPostExecute(Void param) {
Log.d(TAG, "Done!");
mTaskHandler = null;
}
};
mTaskHandler.execute();
}
}
Don't forget to handle this in onPause():
public void onPause() {
super.onPause();
if (mTaskHandler != null) {
mTaskHandler.cancel(true);
// May want to reset buttons too?
}
}