Develop Reference

Android App Crashes with while loop

I'm making this app that tells how much longer till we reach a destination but whenever I try to use it it just black screens just crashes. I think it has something to do with the loop but I can't find anything online Can anyone help? Thanks in advance.................................................................................................................
package com.example.myapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
import java.util.Calendar;
import java.util.TimeZone;
import java.time.*;
import java.math.*;
public class TimeTIll extends AppCompatActivity {
private static final String DateUtils = null;
TextView txt;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_till);
txt = (TextView) findViewById(R.id.TimeDipslay);
int i = 0;
while (i < 10) {
Program();
i++;
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
Thread.currentThread().interrupt();
}
}
}
public void Program() {
int totalMinutesSinceMidnight = 0;
long ms = 0;
long secondsM = 0;
long SecondsTillEstimate = 0;
long SecondsTillArrival1 = 0;
double MinutesTillArrival = 0;
double hoursTillArrival = 0;
double SecondsTillArrival = 0;
Calendar now = Calendar.getInstance();
Calendar midnight = Calendar.getInstance();
midnight.set(Calendar.HOUR_OF_DAY, 0);
midnight.set(Calendar.MINUTE, 0);
midnight.set(Calendar.SECOND, 0);
midnight.set(Calendar.MILLISECOND, 0);
try {
Thread.sleep(2000);
} catch (InterruptedException ex) {
Thread.currentThread().interrupt();
}
now = Calendar.getInstance();
midnight = Calendar.getInstance();
ms = now.getTime().getTime() - midnight.getTime().getTime();
totalMinutesSinceMidnight = (int) (ms / 1000);
secondsM = totalMinutesSinceMidnight;
SecondsTillEstimate = (60 * 60 * 23);
SecondsTillArrival1 = SecondsTillEstimate - secondsM;
hoursTillArrival = Math.floor(SecondsTillArrival1 / 3600);
SecondsTillArrival1 -= (hoursTillArrival * 3600);
MinutesTillArrival = Math.floor(SecondsTillArrival1 / 60);
SecondsTillArrival1 -= (MinutesTillArrival * 60);
SecondsTillArrival = SecondsTillArrival1;
txt.setText((int) hoursTillArrival + " Hours " + (int) MinutesTillArrival + " Minutes " + (int) SecondsTillArrival + " Seconds Till Arrival In Floriada");
}
}

Please read about the activity life-cycle. You cannot call long-running tasks in onCreate and expect them to show anything other than an ANR crash (your onCreate method blocks the UI thread with all those sleep statements and generates an ANR crash before it even gets to the onStart and onResume stages where it actually shows the activity).
If you want the UI to change dynamically, you could use a handler to execute a method at a regular interval. For example, to update something at a regular interval (1000 ms here) you could do:
public class MainActivity extends AppCompatActivity {
private final Handler handler = new Handler();
private TextView txt;
private int count = 0;
private final int updateFreqMs = 1000; // call update every 1000 ms
#Override
protected void onPause() {
super.onPause();
handler.removeCallbacksAndMessages(null);
}
#Override
protected void onResume() {
super.onResume();
handler.postDelayed(new Runnable() {
#Override
public void run() {
updateTime();
handler.postDelayed(this, updateFreqMs);
}
}, updateFreqMs);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_time_till);
txt = findViewById(R.id.TimeDipslay);
}
private void updateTime() {
// here you update the displayed value
// this will be called every second indefinitely
// do your math and generate a string to print, just showing
// a counter here to demonstrate
++count;
txt.setText("Count = " + count);
}
}

I think that the problem is that you are trying to make sleep the main thread of the application. In Android I knew that for security reasons this can't be done.
(Look this https://www.codementor.io/tips/0743378261/non-freezing-sleep-in-android-app for details )
Try this solution instead:
How to pause / sleep thread or process in Android?

You Shouldn`t use it inside main thread specially when you are doing operation inside it.
You may have to use some thing like that.
viewModelScope.launch(Dispatchers.IO) {
while (statues==true){
if (statue==true){
delay(500)
//ToDo
}
}
}

Android CountDownTimer and Runnable

what I'm trying to do:
My app connects with a Bluetooth accelerometer and gets acceleration data every 50ms. I want to check for these with a Runnable. And this worked fine. However, for the complete app I added two CountDownTimers:
1) introTimer(), which runs in an AlertDialog and counts down from 3. OnFinish() calls (i) my Runnable, that deals with new acceleration data and (ii) a second timer called
2) mainTimer(), which counts down from 20 and refreshes a TextView on the UI.
My problem is, that my Runnable is only executed once when it is first called. Why is that? Apparently I have not yet understood the threading principles behind this. My next step (probably going to be complicated) is to refresh ImageViews every 50ms (or maybe less often, but still with a relatively high frequency) on the UI, depending on the accelerometer data.
I have thought about deleting the Runnable and putting my calculations in the CountDownTimer, but this might be difficult or inaccurate with the timing/frequency/periods. What do you think?
Here are the code parts. If you think other parts are relevant, I can post them as well:
startButton.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
LayoutInflater layoutInflater = getActivity().getLayoutInflater();
View promptView = layoutInflater.inflate(R.layout.intro_timer_prompt, null);
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
final TextView introTimer = (TextView) promptView.findViewById(R.id.introTimer);
builder.setView(promptView);
AlertDialog alertD = builder.create();
alertD.show();
introTimer(introTimer, alertD);
}
private void introTimer(final TextView introTimer, final AlertDialog alertD) {
new CountDownTimer(4*1000, 1000) {
public void onTick(long millisUntilFinished) {
introTimer.setText( ""+ (millisUntilFinished / 1000));
}
public void onFinish() {
alertD.cancel();
// mainTimer();
clearArrayLists();
mHandler = new Handler();
mHandlerTask.run();
mainTimer();
}
}.start();
}
private void mainTimer() {
new CountDownTimer((int)DURATION*1000, 10) {
public void onTick(long millisUntilFinished) {
//mTimerView.setText("seconds remaining: " + millisUntilFinished / 1000 + ":" + millisUntilFinished / 1000. );
long millisecs = Math.round(millisUntilFinished % 1000 / 100);
mTimerView.setText("seconds remaining: " + millisUntilFinished / 1000 + ":" + millisecs );
}
public void onFinish() {
String energy = new DecimalFormat("#.##").format(accumulatedKineticEnergy.get(accumulatedKineticEnergy.size()-1));
mTimerView.setText("Accumulated Energy is " + energy + " Joule.");
}
}.start();
}
Runnable mHandlerTask = new Runnable() {
#Override
public void run() {
Log.i(TAG, "executed only once :( ");
if (a_x.size() < DURATION/INTERVAL) {
try {
calcAccList();
//...calc things...;
mHandler.postDelayed(this, (long) (1000*INTERVAL));
} catch (Exception e) {
e.getMessage();
}
}
else {
mHandler.removeCallbacks(mHandlerTask);
}
}
};

A countdown timer doesn't repeat itself when it expires, but you need to start it again. Maybe you can use the AlarmManager in this case to have a better design.

Timer function in Service (kind of chronometer)

My intention is to create an timer which starts from 00:00:00 and hangs together with a recording function. This recording is done in a service so, the timer is also in the same service. If the app moves to the background, the recording and thus the timer keep on going and the app picks the time up at the onResume with a myService.getTime().
But I experience two strange things. The first is that my timer sometimes goed faster than a second, sometimes slower, sometimes jumps from for example 00:00:04 to 00:00:06 etc. There is no consitency in it. I use the code below, but there might be a better option to solve this? The second is that it is causing a lag on my button, although I am starting it in a service?
SERVICE
//////////TIMER FUNCTION START//////////
private void startTimerClick() {
if (stopped) {
startTime = System.currentTimeMillis() - elapsedTime;
} else {
startTime = System.currentTimeMillis();
}
mHandler.removeCallbacks(startTimer);
mHandler.postDelayed(startTimer, 0);
}
private void pauseTimerClick() {
mHandler.removeCallbacks(startTimer);
stopped = true;
}
private void stopTimerClick() {
mHandler.removeCallbacks(startTimer);
stopped = false;
}
private void startTimer() {
startTimer = new Runnable() {
public void run() {
elapsedTime = System.currentTimeMillis() - startTime;
updateTimer(elapsedTime);
mHandler.postDelayed(this, REFRESH_RATE);
}
};
}
private void updateTimer(float time) {
secs = (long) (time / 1000);
mins = (long) ((time / 1000) / 60);
hrs = (long) (((time / 1000) / 60) / 60);
/*
* Convert the seconds to String and format to ensure it has a leading
* zero when required
*/
secs = secs % 60;
seconds = String.valueOf(secs);
if (secs == 0) {
seconds = "00";
}
if (secs < 10 && secs > 0) {
seconds = "0" + seconds;
}
/* Convert the minutes to String and format the String */
mins = mins % 60;
minutes = String.valueOf(mins);
if (mins == 0) {
minutes = "00";
}
if (mins < 10 && mins > 0) {
minutes = "0" + minutes;
}
/* Convert the hours to String and format the String */
hours = String.valueOf(hrs);
if (hrs == 0) {
hours = "00";
}
if (hrs < 10 && hrs > 0) {
hours = "0" + hours;
}
}
//////////TIMER FUNCTION END////////////
public String getHours(){
return hours;
}
public String getMinutes(){
return minutes;
}
public String getSeconds(){
return seconds;
}
}
ACTIVITY(/FRAGMENT)
private void timerStart() {
handler = new Handler();
Thread t = new Thread() {
#Override
public void run() {
try {
while (!isInterrupted()) {
Thread.sleep(1000);
handler.post(new Runnable() {
#Override
public void run() {
timer.setText(myService.getHours()+":"+myService.getMinutes()+":"+myService.getSeconds());
}
});
}
} catch (InterruptedException e) {
}
}
};
t.start();
}

You are using Threads both in your Service and in your Activity/Fragment code.
Using threads for time sensitive tasks in Android is a problem because Android is able to significantly delay threads.
I have been using a ScheduledThreadPoolExecutor for a similar task and it worked great.
You are then using it like this:
ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1); // where 1 is the number of needed concurrent threads. 1 should last for your needs.
executor.scheduleWithFixedDelay(new TimerTask() {
// your recurringly executed code here
}, 0, 1, TimeUnit.SECONDS);

Countdown timer not looping

Basically I am doing a cardio feature and have three countdown timers in a row nested within each other, so when one timer finishes, the next one starts. One for preparation time, one for workout time and one for rest time, the user chooses the times of these.
I need it to loop however many times the user selects from a numberpicker, but no matter what I do it only goes through it once and doesn't loop so I know it all works it's just the looping part that doesn't work.
Am I missing something here? Is there a better way to do this?
//Main countdown timers loop
for(int i = 0; i <= times.getValue() + 1; i++) //times NumberPicker
{
prepCountTimer = new CountDownTimer(_finalPrep * 1000, 1000) {
public void onTick(long millisUntilFinished) {
tvRoundCount.setText("Round " + roundCount + " / " + times.getValue());
tvCountDown.setText((millisUntilFinished / 1000) + "s");
if(millisUntilFinished <= (6 * 1000))
{
tvCountDown.setTextColor(Color.RED);
}
}
public void onFinish() {
workoutCountTimer = new CountDownTimer(_finalWorkout * 1000, 1000) {
public void onTick(long millisUntilFinished) {
tvCountDown.setTextColor(Color.GREEN);
tvCountDown.setText((millisUntilFinished / 1000) + "s");
if(millisUntilFinished <= 6 * 1000)
{
tvCountDown.setTextColor(Color.RED);
}
}
public void onFinish() {
restCountTimer = new CountDownTimer(_finalRest * 1000, 1000) {
public void onTick(long millisUntilFinished) {
tvCountDown.setTextColor(Color.GREEN);
tvCountDown.setText((millisUntilFinished / 1000) + "s");
if(millisUntilFinished <= 6 * 1000)
{
tvCountDown.setTextColor(Color.RED);
}
}
public void onFinish() {
roundCount = roundCount + 1;
}
}.start();
}
}.start();
}
}.start();
}

the issue here is that you create prepCountTimer and assign on finish ect, then start it. then it reaches the end of for each and loops again making another preopCountTimer and starting it. you need to make your restCountTimer start the next preopCountTimer once it's done. unless I'm understanding something wrong here.
public void callingMethod() {
timerMethod(times.getValue());
// execution continues as your timer will run in a different thread
}
public void timerMethod(final int count) {
if (count == 0) {
// we have done the number of timers we want we can
// call whatever we wanted to once our timers were done
}
//you could use count to get the times for each timer here
startTimer(_finalPrep, new timerListner() {
#Override
public void timerFinish() {
//when timer 1 finishes we will start timer 2
startTimer(_finalWorkout, new timerListner() {
#Override
public void timerFinish() {
//when timer 2 finishes we will start timer 3
startTimer(_finalRest, new timerListner() {
#Override
public void timerFinish() {
//when timer 3 finishes we want to call the next timer in the list.
timerMethod(count - 1);
}
});
}
});
}
});
}
private interface timerListner {
void timerFinish();
}
public void startTimer(int timerTime, final timerListner onFinish) {
// you can pass in other parameters unqiue to each timer to this method aswell
CountDownTimer timer = new CountDownTimer(timerTime * 1000, 1000) {
public void onTick(long millisUntilFinished) {
tvRoundCount.setText("Round " + roundCount + " / " + times.getValue());
tvCountDown.setText((millisUntilFinished / 1000) + "s");
if (millisUntilFinished <= (6 * 1000)) {
tvCountDown.setTextColor(Color.RED);
}
}
#Override
public void onFinish() {
onFinish.timerFinish();
}
};
timer.start();
}

What is my app getting force close? There is some error with the thread. But i'm not able to figure it out? [closed]

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.
Closed 10 years ago.
public class MainActivity extends Activity {
private Button Start, Reset, Stop;
private EditText stop_watch, lblDate, lblTime;
public MainActivity() {
init();
}
private final UpdateClockThread ucThread = new UpdateClockThread();
private final StopwatchThread swThread = new StopwatchThread();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Start = (Button)findViewById(R.id.button1);
Stop = (Button)findViewById(R.id.button3);
Reset = (Button)findViewById(R.id.button2);
stop_watch = (EditText)findViewById(R.id.editText3);
lblTime = (EditText)findViewById(R.id.editText2);
lblDate = (EditText)findViewById(R.id.editText1);
Start.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
startactionPerformed();
}
});
Stop.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
stopactionPerformed();
}
});
Reset.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
resetactionPerformed();
}
});
}
public void init() {
swThread.setDaemon(true);
ucThread.setDaemon(true);
swThread.start();
ucThread.start();
}
/** Listens to the Start/Stop/Resume button. */
void startactionPerformed() {
swThread.go();
//init();
}
void stopactionPerformed() {
swThread.noGo();
}
void resetactionPerformed() {
swThread.reset();
}
/** A thread that updates the current date & time. */
private class UpdateClockThread extends Thread {
/** The actual work of the thread. */
public void run() {
while (true) {
lblTime.setText("ampm");
Calendar now = Calendar.getInstance();
String month = Integer.toString(now.get(Calendar.MONTH)+1);
String date = Integer.toString(now.get(Calendar.DAY_OF_MONTH));
String year = Integer.toString(now.get(Calendar.YEAR));
String hour = Integer.toString(now.get(Calendar.HOUR));
if (hour.equals("0")) hour = "12";
String minute = Integer.toString(now.get(Calendar.MINUTE));
if (minute.length() == 1) minute = "0" + minute;
String second = Integer.toString(now.get(Calendar.SECOND));
if (second.length() == 1) second = "0" + second;
String ampm = now.get(Calendar.AM_PM) == Calendar.AM ? "AM" : "PM";
lblDate.setText(month + "/" + date + "/" + year);
lblTime.setText(hour + ":" + minute + ":" + second + " " + ampm);
try {
sleep(500);
} catch (InterruptedException e) {}
}
}
}
/** A thread that keeps track of the stop watch & updates
* the display accordingly.
*/
class StopwatchThread extends Thread {
/** Whether or not stop watch is running. */
private boolean going = false;
/** Stores elapsed milliseconds of previous runs. */
private long prevElapsed = 0;
/** Stores beginning time of this run. */
private Date startDate = new Date();
/** Returns elapsed time in milliseconds.
*#return The elapsed time
*/
private long elapsedTime() {
return prevElapsed + (going ? new Date().getTime() - startDate.getTime() : 0);
}
/** Changes the number of elapsed milliseconds into a string.
*#param time Number of elapsed milliseconds
*#return The elapsed time as a string.
*/
private String msToString(long time) {
String ms, sec, min;
if (time % 10 >= 5) //round to nearest hundredth
time += 5;
ms = Long.toString(time % 1000);
while (ms.length() < 3)
ms = "0" + ms;
ms = ms.substring(0, ms.length() - 1);
time /= 1000;
sec = Long.toString(time % 60);
if (sec.length() == 1) sec = "0" + sec;
time /= 60;
min = Long.toString(time);
return min + ":" + sec + "." + ms;
}
/** Called when the stop watch is to go.
*/
public void go() {
startDate = new Date();
going = true;
}
/** Called when the stop watch is to stop.
*/
public void noGo() {
prevElapsed = elapsedTime();
going = false;
}
/** Resets the stop watch.
*/
public void reset() {
going = false;
prevElapsed = 0;
}
/** Adds a lap to the list.
*/
/** Main code of the thread.
*/
public void run() {
while (true) {
stop_watch.setText(msToString(elapsedTime()));
yield();
}
}
}
}
What is my app getting force close? There is some error with the thread. But i'm not able to figure it out?

Try make all interaction with UI from threads in runOnUiThread method of Activity http://developer.android.com/reference/android/app/Activity.html#runOnUiThread%28java.lang.Runnable%29
EDIT
private class UpdateClockThread extends Thread {
public void run() {
/* Do somthing expensive */
......
/* Update UI */
MainActivity.this.runOnUiThread(new Runnable() {
#Override
public void run() {
/* Do UI update */;
lblTime.setText("ampm");
......
}
});
}
}

You should run adb logcat on your developer machine. Usually if you get a force close a traceback is displayed in the log.

Your class StopwatchThread contains the line:
stop_watch.setText(msToString(elapsedTime()));
This will not work, and neither will the UI updates within UpdateClockThread. This is because you cannot modify the UI from a background thread. Your background thread should either:
send a message to a Handler that has been created on the UI thread, so that the Handler then makes the update to the UI, or
you can pass a runnable into runOnUiThread that performs the UI update.