Develop Reference

Timing threads on Android

I try to build an app, that vibrates with a certain pattern depending on the value of a variable that comes constantly with a stream from a video game.
I managed to display telemetry data on the TextView continiously. What I want is the phone to vibrate for a certain lenght in ms or pattern, depending on the value of gforce in Thread2. What I would like to achieve is, the following sequence. Read the stream, display ias, gforce and vertical on the TextView, check gforce value, if value>=2, vibrate(choose length or pattern by gforce value), pause 500ms, repeat.
I know about the lack of connection security in my code, but that is something for later.
I do have the problem of thread management here, that I cant solve. The stream comes from a Java server socket and has an output of around one line per ms.
This the code I try to make that work with.
public class MainActivity extends AppCompatActivity {
Thread Thread1 = null;
EditText etIP, etPort;
TextView tvMessages;
String SERVER_IP;
int SERVER_PORT;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
etIP = findViewById(R.id.etIP);
etPort = findViewById(R.id.etPort);
etIP.setText("192.168.178.61");
etPort.setText("31091");
tvMessages = findViewById(R.id.tvMessages);
Button btnConnect = findViewById(R.id.btnConnect);
btnConnect.setOnClickListener(new View.OnClickListener() {
#RequiresApi(api = Build.VERSION_CODES.O)
#Override
public void onClick(View v) {
tvMessages.setText("");
SERVER_IP = etIP.getText().toString().trim();
SERVER_PORT = Integer.parseInt(etPort.getText().toString().trim());
Thread1 = new Thread(new Thread1());
Thread1.start();
}
});
}
PrintStream output;
BufferedReader input;
Socket socket;
String message;
class Thread1 implements Runnable {
#Override
public void run() {
try {
socket = new Socket(SERVER_IP, SERVER_PORT);
socket.setTcpNoDelay(true);
output = new PrintStream(socket.getOutputStream(), true);
input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
runOnUiThread(new Runnable() {
#Override
public void run() {
tvMessages.setText("Connected\n");
}
});
new Thread(new Thread2()).start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
class Thread2 implements Runnable {
private double ias;
private double gforce;
private double vertical;
#Override
public void run() {
while (!(socket.isClosed())) {
try {
message = input.readLine();
if (message != null && message.contains("IAS")) {
ias = Double.parseDouble(message.substring(5, (message.indexOf(" ", 5))));
gforce = Double.parseDouble(message.substring(message.indexOf("Gy:") + 4, message.indexOf("Gz:") - 1));
vertical = Double.parseDouble(message.substring(message.indexOf("vertical:") + 10, message.indexOf("Gx:") - 1));
}
if (message != null && !(message.equals("exit"))) {
runOnUiThread(new Runnable() {
#Override
public void run() {
System.out.println(message);
tvMessages.setText("IAS: " + ias + "\n" +
"G: " + gforce + "\n" +
"Vertical: " + vertical + "\n");
}
});
//do trigger Vibration handler and make the phone vibrate in a pattern relative to gforce
new VibrationHandler((int)gforce).start();
//at this point sleep for n ms
} else {
Thread1 = new Thread(new Thread1());
Thread1.start();
return;
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
class VibrationHandler extends Thread{
int pattern;
public VibrationHandler(int pattern){
this.pattern=pattern;
}
public void run(){
Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
// Vibrate for 500 milliseconds
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
v.vibrate(VibrationEffect.createOneShot(pattern*50, VibrationEffect.DEFAULT_AMPLITUDE));
} else {
//deprecated in API 26
v.vibrate(pattern*50);
}
}
}
}
Thank you a lot for your help.

Cpu usage is too high, Up to 95%

My project has a demand, need to constantly read the bar code data, like a commodity supermarket scanner with bar code scanning guns, then data into a keypad, but encountered a problem, for a long time continuously scanning, CPU usage will be very high, even reached 95%, I have set the thread to sleep in a loop, but failed to solve this problem.
I have been asking for this problem, but it may be too messy code, affecting everyone to read, and now simplify the code, I hope you can help me, thank you very much;
Sometimes a few hours on the CPU scan occupy too high, but sometimes a few days there. Grab logcat log found the sleep method sometimes is not executed, if not continuous execution will cause CPU use rate is too high, but I don't know why the sleep method will not perform .
private void startReceive() {
stopReceive = false;
new Thread(new Runnable() {
#Override
public void run() {
int timeout = 1000;
while (!stopReceive) {
if (mUsbDeviceConnection != null) {
try {
byte[] receiveBytes = new byte[64];
int value = mUsbDeviceConnection.bulkTransfer(mUsbEndpoint, receiveBytes,
receiveBytes.length, timeout);
if (value > 0) {
for (int i = 2; !stopReceive && i < receiveBytes.length; i++) {
byte b = receiveBytes[i];
if (b != 0) {
result += new String(new byte[]{b});
}
if (!stopReceive && !result.equals("") && result != null) {
Runtime.getRuntime().exec("input text " + result);
}
}
}
Thread.sleep(100);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
}).start();
}

This seemd to be a huge thread running on the main-thread which will drastically slow down the performance of the device.
Big operations you should instead run asynchronously, which means that it will run in the background-thread and not affect the UI-thread which is the issue right now:
Here's a example of how the implementation would look like:
private class LongOperation extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
// StartReceive code..
stopReceive = false;
new Thread(new Runnable() {
#Override
public void run() {
int timeout = 1000;
while (!stopReceive) {
if (mUsbDeviceConnection != null) {
try {
byte[] receiveBytes = new byte[64];
int value = mUsbDeviceConnection.bulkTransfer(mUsbEndpoint, receiveBytes,
receiveBytes.length, timeout);
if (value > 0) {
for (int i = 2; !stopReceive && i < receiveBytes.length; i++) {
byte b = receiveBytes[i];
if (b != 0) {
result += new String(new byte[]{b});
}
if (!stopReceive && !result.equals("") && result != null) {
Runtime.getRuntime().exec("input text " + result);
}
}
}
Thread.sleep(100);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
}
}).start();
return "Done";
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// We're done
}
#Override
protected void onPreExecute() {
// Before starting operation
}
#Override
protected void onProgressUpdate(Void... values) {
}
}
How to start the thread:
LongOperation longOp = new LongOperation();
longOp.execute();
Read more: AsyncTask Android example

You should better look this post and try to find which method consume more system resource: https://stackoverflow.com/a/14688291/6176003

Wait for thread to finish and then move to next position

i am trying to display a Toast on the screen and when Toast fades off then move to the next question. I have tried with Thread but cannot seem to manage.
My code:
next.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (getUserSelection()){
position = position + 3;
if (position < questionsArray.size()) {
curName = questionsArray.get(position).getName();
curArray = questionsArray.get(position).getAnswers();
curIscorrect = questionsArray.get(position).getIscorrect();
setupQuestionView(curName, curArray, curIscorrect);
} else {
StringGenerator.showToast(QuestionsActivity.this, "Your score : " + score + "/" + (questionsArray.size() / 3));
}
}else {
StringGenerator.showToast(QuestionsActivity.this, getString(R.string.noanswerselected));
}
}
});
and the getUserSelectionMethod:
private boolean getUserSelection() {
correct = (RadioButton)findViewById(group.getCheckedRadioButtonId());
if (correct == null){
return false;
}else {
correctAnswerText = correct.getText().toString();
if (map.get(correctAnswerText).equals(Constants.CORRECTANSWER)) {
score++;
setCorrectMessage();
return true;
} else {
setWrongMessage();
return true;
}
}
}
private void setCorrectMessage() {
correctToast = new Toast(QuestionsActivity.this);
correctToastView = getLayoutInflater().inflate(R.layout.correct, (ViewGroup) findViewById(R.id.correctRootLayout));
correctText = (TextView)correctToastView.findViewById(R.id.correctTextView);
correctText.setText(getString(R.string.correctAnswer));
correctToast.setDuration(Toast.LENGTH_SHORT);
correctToast.setView(correctToastView);
correctToast.show();
correctThread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
correctToast.cancel();
}
});
correctThread.start();
}
private void setWrongMessage() {
wrongToast = new Toast(QuestionsActivity.this);
wrongToastView = getLayoutInflater().inflate(R.layout.wrong, (ViewGroup) findViewById(R.id.wrongRootLayout));
wrongText = (TextView)wrongToastView.findViewById(R.id.wrongTextView);
wrongText.setText(getString(R.string.wrongAnswer));
wrongToast.setDuration(Toast.LENGTH_SHORT);
wrongToast.setView(wrongToastView);
wrongToast.show();
wrongThread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
wrongToast.cancel();
}
});
wrongThread.start();
}
Any suggestion on how to do this?

You can determine the toast visibility:
toast.getView().getWindowToken()
If the result is null, than your toast isn't visible anymore, and than you can run any code you want.

as stated in this answer you can start a thread that waits the duration of the Toast:
Thread thread = new Thread(){
#Override
public void run() {
try {
Thread.sleep(3500); // 3.5seconds!
// Do the stuff you want to be done after the Toast disappeared
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
Toast.LENGTH_SHORT and Toast.LENGTH_LONG are only flags so you have to either hard code the duration or keep them in a constant. The durations are 3.5s (long) and 2s (short).
If you want to manipulate some of your views, you cannot do this in another thread than the "main" UI thread. So you have to implement a kind of callback/polling mechanism to get notified when the SleepThread has finished.
Check this answer to read about a couple of ways to do this. Probably the easiest of them to understand and implement is this:
After you started your Thread you can check if it is still alive and running by calling thread.isAlive(). In this way you can do a while loop that runs while the thread is running:
// start your thread
while(thread.isAlive()){}
// continue the work. The other thread has finished.
Please note that this is NOT the most elegant way to do this! Check the other possibilities in the answer I've mentioned above for more elegant solutions (especially the last one with the listeners is very interesting and worth reading!)

That's because the Thread class is purely executed in the background and you need to manipulate the view in the Main thread. To solve your issue just replace the Thread with AsynTask.
AsyncTask<Void,Void,Void> a = new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
correctToast.cancel();
}
};
a.execute();
If you look at my code you can see my onPostExecute, this method is called in the Main Thread.

My Error was because i was trying to acess UI Elements through another Thread so modifying the code like this:
Thread thread = new Thread(new Runnable() {
#Override
public void run() {
try {
Thread.sleep(500);
QuestionsActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
moveToNextQuestion();
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
thread.start();
did the trick. I hope my answer helps someone!!!

What is the correct way to start and stop thread

I need to write following. When button is clicked new thread should be start. Run method is infinite loop which changes for instanse text in TextView, and when I press button again it should stop changing text.
Please help how to do this in the correct way without dangerous methods.
Thx in advance .

private Thread t;
private String threadName;
private boolean suspended = false;
public void run() {
System.out.println("Running " + threadName );
try {
for(int i = 10; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
// Let the thread sleep for a while.
Thread.sleep(300);
synchronized(this) {
while(suspended) {
wait();
}
}
}
} catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start () {
System.out.println("Starting " + threadName );
if (t == null) {
t = new Thread (this, threadName);
t.start ();
}
}
void suspend() {
suspended = true;
}
synchronized void resume() {
suspended = false;
notify();
}

Its not really clear what you want to do for me.
But I bet you can do it using AsyncTask with doInBackground and onProgressUpdate, take a look.

Android listview timer run in every second

I have a issue with using a timer on a listview.
In the list item I showed using sqlite values. There is a textview which showing time difference of last updated time of the data and current time. i have to show it in every one second. so the user can know how long he updated the record.
I tried this in several ways.
First way
I tried to add timer in adapter class. so for every item new timer is created. so application crashed because of many timers run simultaneously.
Second way
I tried using adapter.notifyDataSetChanged() way. Like as this.
Handler timerHandler = new Handler();
Runnable timerRunnable = new Runnable() {
#Override
public void run() {
if (adapterChatThread != null) {
adapter.notifyDataSetChanged();
}
timerHandler.postDelayed(this, 1000); // run every second
}
};
timerRunnable.run();
I move to another activity when click on list item and user can come back to this Activity.
so in Onresume I used
timerHandler.postDelayed(timerRunnable, 500);
and OnPause
timerHandler.removeCallbacks(timerRunnable);
Issue is data is not showing well. I mean in every second data difference is not one second. some time differnce is 2sec, 5 sec, .. etc.
means timer is not working as I expected.
Third way
I used a asynctask and call it in every second using a timer.
class ThreadTimer extends AsyncTask<Void, Void, Void> {
#Override
protected Void doInBackground(Void... params) {
return null;
}
#Override
protected void onPostExecute(Void result) {
if (adapter != null)
adapter.notifyDataSetChanged();
super.onPostExecute(result);
}
}
I called this as in here
Handler timerHandler = new Handler();
Runnable timerRunnable = new Runnable() {
#Override
public void run() {
new ThreadTimer().execute();
timerHandler.postDelayed(this, 1000); // run every second
}
};
timerRunnable.run();
previous issue triggered. (data not showing well)
Fourth way
Using AsyncTask as this
class ThreadTimer extends AsyncTask<Void, Void, Void> {
void Sleep(int ms) {
try {
Thread.sleep(ms);
} catch (Exception e) {
}
}
#Override
protected Void doInBackground(Void... params) {
while (threadRun) {
Sleep(1000);
return null;
}
return null;
}
#Override
protected void onPostExecute(Void result) {
adapter.notifyDataSetChanged();
super.onPostExecute(result);
}
}
I called this class in OnResume.
In on pause I set threadRun= false;
issue is same.
please help me.
My requirement is update list item in every second.
Thank you.
edit
here is my adapter class textview update code.
Date lastUpdatedTime;
final ChatThreadDAO ctd = new ChatThreadDAO();
long timeForNextResponse = ctd.getLastRespondedTime(vct.get(position).getThread_id());
try {
if (vct.get(position).getThread_read_status() == 1 && timeForNextResponse > 0) {
final long respTime = timeForNextResponse;
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
lastUpdatedTime = formatter.parse(vct.get(position).getLast_updated_time());
final long timeDiff = (new Date()).getTime() - lastUpdatedTime.getTime();
if (timeDiff <= respTime) {
timeForNextResponse = respTime - timeDiff;
ctd.updateTimeRespondToLastMsg(vct.get(position).getThread_id(), timeForNextResponse);
holder.tvChatTimer.setVisibility(View.VISIBLE);
holder.tvChatTimer.setText(timeForNextResponse / 1000 + "");
} else {
ctd.updateTimeRespondToLastMsg(vct.get(position).getThread_id(), 0);
}
} else {
holder.tvChatTimer.setVisibility(View.INVISIBLE);
}
} catch (ParseException e) {
e.printStackTrace();
}
here vct is
Vector vct;
I assign the values to vector in adapter class constructer.

Here is an example similar to your case.
private class connectionControl extends Thread {
boolean stop_ = false;
public void stop_() {
this.stop_ = true;
}
public void run() {
System.out.println("Thread started:" + getClass().getSimpleName());
while(!this.stop_) {
try {
Thread.sleep(1000);
runOnUiThread(new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
Calendar c = Calendar.getInstance();
int rightNow = c.get(Calendar.SECOND) + c.get(Calendar.MINUTE)*60;
if(rightNow - lastUpdatedTime > 10) {
wirelessIcon.setImageResource(R.drawable.wirelessred);
}
else if(rightNow - lastUpdatedTime > 5) {
wirelessIcon.setImageResource(R.drawable.wirelessyellow);
}
else {
wirelessIcon.setImageResource(R.drawable.wirelessgreen);
}
}
});
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println("Thread stoped:" + getClass().getSimpleName());
}
}
You set your lastUpdatedTime the same way you created rightNow whenever you call notifyDataSetChanged() method of your adapter.