Develop Reference

Countdowntimer cancel crashes the app when click on button

I am trying to create a countDownTimer but, whenever I click on the button the app crashes.
I want that if I click on player1 button player2 countdown should pause and vice versa for player2.
The Error I am getting:
Attempt to invoke virtual method 'void
android.os.CountDownTimer.cancel()' on a null object reference
Here is the Code
public class Timer extends AppCompatActivity {
Button player1, player2;
long incrementTime = 3000;
int time;
long timeinLong;
ImageButton pause;
CountDownTimer player1count, player2count;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_timer);
player1 = findViewById(R.id.player1);
player2 = findViewById(R.id.player2);
Intent intent = getIntent();
time = intent.getIntExtra("time", 0);
timeinLong = time * 60000;
int minutes = (int) (timeinLong / 1000) / 60;
int seconds = (int) (timeinLong / 1000) % 60;
String timeFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);
player1.setText(timeFormatted);
player1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startCountDown(player1);
player2count.cancel();
}
});
player2.setText(timeFormatted);
player2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startCountDown2(player2);
player1count.cancel();
}
});
}
private void startCountDown(final Button button) {
player1count = new CountDownTimer(timeinLong, 1000) {
#Override
public void onTick(long millisUntilFinished) {
timeinLong = millisUntilFinished;
updateCountDownText(button);
}
#Override
public void onFinish() {
timeinLong = 0;
updateCountDownText(button);
}
}.start();
}
private void startCountDown2(final Button button) {
player2count = new CountDownTimer(timeinLong, 1000) {
#Override
public void onTick(long millisUntilFinished) {
timeinLong = millisUntilFinished;
updateCountDownText(button);
}
#Override
public void onFinish() {
timeinLong = 0;
updateCountDownText(button);
}
}.start();
}
private void updateCountDownText(Button button) {
int minutes = (int) (timeinLong / 1000) / 60;
int seconds = (int) (timeinLong / 1000) % 60;
String timeFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);
button.setText(timeFormatted);
if (timeinLong < 30000) {
button.setTextColor(Color.RED);
} else {
button.setTextColor(Color.BLACK);
}
}
#Override
protected void onDestroy() {
super.onDestroy();
if (player1count != null) {
player1count.cancel();
}
}
}

player2count only gets initialized inside startCountDown2, which is only called inside player2.setOnClickListener. Hence, if you click on the player1 button before ever clicking on player2 button, you'll get a NullPointerException, since calling player2count.cancel() on a not-yet-initialized player2count is not allowed. To prevent this from happening, it would be appropriate to just check for null in this case:
if (player2count != null) {
player2count.cancel();
}

Just don't cancel timers unless they're intialized, it will bring NPE, so check if they're not null in both players as below
player1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startCountDown(player1);
if (player2count != null)
player2count.cancel();
}
});
player2.setText(timeFormatted);
player2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startCountDown2(player2);
if (player1count != null)
player1count.cancel();
}
});

you don't initialize that when click listener called
i fixed it for myself by add try catch on .cancel lines
or set
if (player1count != null)
...

In android progressar resets it value when app is in background

I have a counter with a circular progress bar. When the counter starts, the progress bar is also starting from counter value, but when it's running in the background and again open app... the circular progress bar starts from 0, but the counter runs correctly as per value. In this case I need the progress bar not to start from 0.
here is my code:
public class MainActivity extends AppCompatActivity {
public int counter;
Button button;
public boolean isrunningtime = false;
TextView textView;
private ProgressBar progressBar;
long millisUntilFinished = 0;
SharedPreferences sharedPreferences;
SharedPreferences.Editor editor;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.textView);
sharedPreferences = getSharedPreferences("my", MODE_PRIVATE);
editor = sharedPreferences.edit();
progressBar = findViewById(R.id.progressBar);
startService(new Intent(this, BroadcastService.class));
Log.i("Tag", "Started service");
}
private BroadcastReceiver br = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
updateGUI(intent); // or whatever method used to update your GUI fields
}
};
#Override
public void onResume() {
super.onResume();
registerReceiver(br, new IntentFilter(BroadcastService.COUNTDOWN_BR));
Log.i("Tag", "Registered broacast receiver");
}
#Override
public void onPause() {
super.onPause();
unregisterReceiver(br);
}
#Override
public void onStop() {
try {
unregisterReceiver(br);
} catch (Exception e) {
// Receiver was probably already stopped in onPause()
}
super.onStop();
}
#Override
public void onDestroy() {
stopService(new Intent(this, BroadcastService.class));
Log.i("Tag", "Stopped service");
super.onDestroy();
}
private void updateGUI(Intent intent) {
if (intent.getExtras() != null) {
millisUntilFinished = intent.getLongExtra("countdown", 0);
Log.i("Tag", "Countdown seconds remaining: " + millisUntilFinished / 1000);
progressBar.setProgress((int) (millisUntilFinished / 1000));
Log.i("progress", "" + (int) (millisUntilFinished / 1000));
textView.setText("" + millisUntilFinished / 1000);
}
}
}

put the unregisterReceiver(br) only in onDestroy() instead of onStop() and onPause()

Remove unregisterReceiver(br); from onStop() and onPause(), And Move registerReceiver(br, new IntentFilter(BroadcastService.COUNTDOWN_BR)); from onResume() to onCreate()

Android two countdown timer overlaps; How to delay the second one?

My code consists of 2 countdown timers, one after finishing says GO! then the other one starts, however the second timer starts immediately, and the GO! message disappears immediately, how to delay the GO! message or the appearing of the second timer? Here's the code.
public class WorkoutGymEasy1 extends Activity {
CountDownTimer cdt = null;
MediaPlayer mp = null;
TextView c;
Button b;
ImageView image;
TextView pushuptext;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.workout_gym_easy1);
final TextView c = (TextView) findViewById(R.id.timer_gym_easy1);
c.setAlpha(0f);
final Button b = (Button) findViewById(R.id.button1);
b.setAlpha(1f);
final ImageView image = (ImageView) findViewById(R.id.imagePushUp);
b.setAlpha(1f);
final TextView pushuptext = (TextView) findViewById(R.id.textPushUp);
b.setAlpha(1f);
RelativeLayout rl5 = (RelativeLayout) findViewById(R.id.rl5);
rl5.setBackgroundColor(Color.BLACK);
mp = MediaPlayer.create(WorkoutGymEasy1.this, R.raw.countdown);
try {
mp.prepare();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
b.setOnClickListener(new OnClickListener() {
public void onClick (View v) {
b.setAlpha(0f);
c.setAlpha(1f);
mp.start();
new CountDownTimer(6000, 1000) { //20 seconds count down with 1s interval (1000 ms) //access TextView element on the screen to set the timer value
public void onTick(long millisUntilFinished) { // Code in this method is executed every 1000ms (1s)
c.setText("" + (millisUntilFinished / 1000) + ""); //update the timer
//if (millisUntilFinished == 0) {
//c.setText("GO!");
//}
}
#Override
public void onFinish() {
// TODO Auto-generated method stub
c.setText("GO!");
// Intent myIntent = new Intent(getApplicationContext(), WorkoutGymEasy2.class);
// startActivity(myIntent);
new CountDownTimer(31000, 1000) { //30 seconds count down with 1s interval (1000 ms) //access TextView element on the screen to set the timer value
public void onTick(long millisUntilFinished) { // Code in this method is executed every 1000ms (1s)
c.setText("" + (millisUntilFinished / 1000) + ""); //update the timer
}
#Override
public void onFinish() {
// TODO Auto-generated method stub
Intent myIntent = new Intent(getApplicationContext(), WorkoutGymEasy2.class);
startActivity(myIntent);
finish(); // call finish() method to destroy this activity and return to instructions screen
}
}.start();
}
}.start();
}
});
}
protected void OnPause() {
super.onPause();
mp.release();
finish();
}
}

You would need 3 timers to simulate a delay. So the first timer would start and finish. Starting the "Go" timer. Then when the "Go" timer is finish, the second official timer would go off.

Countdown timer with pause and resume

I want to do countdown timer with pause and restart.Now i am displaying countdown timer By implenting ontick() and onfinish().please help me out.HEre is th code for countdown timer
final CountDownTimer Counter1 = new CountDownTimer(timervalue1 , 1000)
{
public void onTick(long millisUntilFinished)
{
System.out.println("onTick method!"(String.valueOf(millisUntilFinished/1000)));long s1=millisUntilFinished;
}
public void onFinish()
{
System.out.println("Finished!");
}
}

in onTick method..save the milliseconds left
long s1=millisUntilFinished;
when you want to pause the timer use..
Counter.cancel();
when you want to resume create a new countdowntimer with left milliseconds..
timervalue=s1
counter= new Counter1();
counter.start();
See this link

I would add something to the onTick handler to save the progress of the timer in your class (number of milliseconds left).
In the onPause() method for the activity call cancel() on the timer.
In the onResume() method for the activity create a new timer with the saved number of milliseconds left.
Refer the below links
LINK
LINK

My first answer on stackOverFlow, hope it should help :) ...
This is how I solved the problem, control timer from Fragment, Bottomsheet, Service, Dialog as per your requirement, keep a static boolean variable to control.
declare in your Activity:
long presetTime, runningTime;
Handler mHandler =new Handler();
Runnable countDownRunnable;
Toast toastObj;
public static boolean shouldTimerRun = true;
TextView counterTv;
In onCreate:
presetTime =60000L;
runningTime= presetTime;
//setting up Timer
countDownRunnable=new Runnable() {
#Override
public void run() {
if (shouldTimerRun) //if false, it runs but skips counting
{
counterTv.setText(simplifyTimeInMillis(runningTime));
if (runningTime==0) {
deployToast("Task Completed"); //show toast on task completion
}
runningTime -= 1000;
presetTime = runningTime; //to resume the timer from last position
}
mHandler.postDelayed(countDownRunnable,1000); //simulating on-tick
}
};
mHandler.post(countDownRunnable); // Start our CountdownTimer
Now, whenever you want to pause the timer change the value of shouldTimerRun false and to resume make it true.
#Override
public void onResume() {
super.onResume();
shouldTimerRun=true;
}
#Override
public void onPause() {
super.onPause();
shouldTimerRun=false;
deployToast("Timer is paused !!");
}
Helping methods: (can be skipped)
public static String simplifyTimeInMillis(long time) {
String result="";
long difference = time;
long secondsInMilli = 1000;
long minutesInMilli = secondsInMilli * 60;
long hoursInMilli = minutesInMilli * 60;
if (difference<1000){
return "0";
}
if (difference>=3600000) {
result = result + String.valueOf(difference / hoursInMilli) + "hr ";
difference = difference % hoursInMilli;
}
if (difference>=60000) {
result = result + String.valueOf(difference / minutesInMilli) + "m ";
difference = difference % minutesInMilli;
}
if (difference>=1000){
result = result + String.valueOf(difference / secondsInMilli) + "s";
}
return result;
}
public void deployToast(String msg){
if (toastObj!=null)
toastObj.cancel();
toastObj = Toast.makeText(mContext,msg,Toast.LENGTH_SHORT);
toastObj.show();
}

I'm using two private vars in this case:
private long startPauseTime;
private long pauseTime = 0L;
public void pause() {
startPauseTime = System.currentTimeMillis();
}
public void resumen(){
pauseTime += System.currentTimeMillis() - startPauseTime;
}

I am afraid that it is not possible to pause or stop CountDownTimer and pausing or stopping in onTick has no effect whatsoever user TimerTask instead.
Set up the TimerTask
class UpdateTimeTask extends TimerTask {
public void run() {
long millis = System.currentTimeMillis() - startTime;
int seconds = (int) (millis / 1000);
int minutes = seconds / 60;
seconds = seconds % 60;
timeLabel.setText(String.format("%d:%02d", minutes, seconds));
}
}
if(startTime == 0L) {
startTime = evt.getWhen();
timer = new Timer();
timer.schedule(new UpdateTimeTask(), 100, 200);
}
You can add event listener's like this..
private Handler mHandler = new Handler();
...
OnClickListener mStartListener = new OnClickListener() {
public void onClick(View v) {
if (mStartTime == 0L) {
mStartTime = System.currentTimeMillis();
mHandler.removeCallbacks(mUpdateTimeTask);
mHandler.postDelayed(mUpdateTimeTask, 100);
}
}
};
OnClickListener mStopListener = new OnClickListener() {
public void onClick(View v) {
mHandler.removeCallbacks(mUpdateTimeTask);
}
};
For more refer to Android Documentation.

//This timer will show min:sec format and can be paused and resumed
public class YourClass extends Activity{
TextView timer;
CountDownTimer ct;
long c = 150000; // 2min:30sec Timer
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.YourXmlLayout);
timer = (TextView)findViewById(R.id.Yourtimer)
startTimer(); // it will start the timer
}
public void startTimer(){
ct = new CountDownTimer(c,1000) {
#Override
public void onTick(long millisUntilFinished) {
// Code to show the timer in min:sec form
// Here timer is a TextView so
timer.setText(""+String.format("%02d:%02d",millisUntilFinished/60000,(millisUntilFinished/1000)%60));
c = millisUntilFinished; // it will store millisLeft
}
#Override
public void onFinish() {
//your code here
}
};
ct.start();
}
/*===========================================================
*after creating this you can pause this by typing ct.cancel()
*and resume by typing startTimer()*/

public class MainActivity extends AppCompatActivity {
TextView textView;
CountDownTimer ctimer;
boolean runCountDown;
private long leftTime;
private static final long MILL_IN_FUTURE = 6000;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.text_view);
textView.setText("Click to start");
textView.setOnClickListener(this::clickStartAndPauseAndResume);
leftTime = MILL_IN_FUTURE;
}
public void clickStartAndPauseAndResume(View view) {
if (!runCountDown) {
long time = (leftTime == 0 || leftTime == MILL_IN_FUTURE) ? MILL_IN_FUTURE : leftTime;
ctimer = new CountDownTimer(time, 1) {
#Override
public void onTick(long l) {
leftTime = l;
textView.setText(l + "ms");
}
#Override
public void onFinish() {
textView.setText("Done");
leftTime = 0;
runCountDown = false;
textView.postDelayed(new Runnable() {
#Override
public void run() {
textView.setText("Click to start");
}
}, 1000);
}
}.start();
runCountDown = true;
} else {
ctimer.cancel();
textView.setText(textView.getText() + "\n Click to resume");
runCountDown = false;
}
}
}

A nice and simple way to create a Pause/Resume for your CountDownTimer is to create a separate method for your timer start, pause and resume as follows:
public void timerStart(long timeLengthMilli) {
timer = new CountDownTimer(timeLengthMilli, 1000) {
#Override
public void onTick(long milliTillFinish) {
milliLeft=milliTillFinish;
min = (milliTillFinish/(1000*60));
sec = ((milliTillFinish/1000)-min*60);
clock.setText(Long.toString(min)+":"+Long.toString(sec));
Log.i("Tick", "Tock");
}
The timerStart has a long parameter as it will be reused by the resume() method below. Remember to store your milliTillFinished (above as milliLeft) so that you may send it through in your resume() method. Pause and resume methods below respectively:
public void timerPause() {
timer.cancel();
}
private void timerResume() {
Log.i("min", Long.toString(min));
Log.i("Sec", Long.toString(sec));
timerStart(milliLeft);
}
Here is the code for the button FYI:
startPause.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(startPause.getText().equals("Start")){
Log.i("Started", startPause.getText().toString());
startPause.setText("Pause");
timerStart(15*1000);
} else if (startPause.getText().equals("Pause")){
Log.i("Paused", startPause.getText().toString());
startPause.setText("Resume");
timerPause();
} else if (startPause.getText().equals("Resume")){
startPause.setText("Pause");
timerResume();
}

Stop Current Thread Issue

My Problem is I am Running one Method into Thread and after 30 Seconds I will display alertdialog and click on alertdialog's ok button i will stop current thread but problem is thread is not stop, following is my Code and sorry for bad english comunication
public class CountDownTimerActivity extends Activity implements Runnable {
Thread t;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
t = new Thread(this);
t.start();
}
#Override
public void run() {
// TODO Auto-generated method stub
myTimer.start();
mDeclaration();
myTimer.cancel();
}
private CountDownTimer myTimer = new CountDownTimer(30000, 1000) {
// This will give you 30 sec timer with each tick at 1 second
public void onTick(long millisUntilFinished) {
}
public void onFinish() {
t.interrupt();
//t.stop();
AlertDialog.Builder alert = new AlertDialog.Builder(
CountDownTimerActivity.this);
alert.setMessage("Loading...");
alert.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
});
alert.show();
}
};
public void mDeclaration() {
for (int i = 0; i < 100000; i++) {
System.out.println("Printing OK" + i);
}
}
}

see this question...instead you can put a flag in run method.. and check whether to run or not to run the code in thread.

try this:-
public class CountDownTimerActivity extends Activity implements Runnable {
Thread t;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
t = new Thread(this);
t.start();
}
#Override
public void run() {
// TODO Auto-generated method stub
myTimer.start();
mDeclaration();
myTimer.cancel();
}
private CountDownTimer myTimer = new CountDownTimer(30000, 1000) {
// This will give you 30 sec timer with each tick at 1 second
public void onTick(long millisUntilFinished) {
}
public void onFinish() {
AlertDialog.Builder alert = new AlertDialog.Builder(
CountDownTimerActivity.this);
alert.setMessage("Loading...");
alert.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
// t.interrupt();
t.stop();
}
});
alert.show();
}
};
public void mDeclaration() {
for (int i = 0; i < 100000; i++) {
System.out.println("Printing OK" + i);
}
}
}