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)
...

Kill audio after deliberate or accidental exit of dialog

This is part of the code in my MainActivity.
stopwatch1 is an image button called in MainActivity:
stopwatch1 = (ImageButton)findViewById(R.id.stopwatch1);
I have tried searching for clues on how to use dialog.setOnDismissListener, however, there aren't proper answers to help me with the killing of the audio after deliberate or accidental exit of the dialog. Any help would be appreciated.
stopwatch1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final Dialog mmDialog1 = new Dialog(context);
mmDialog1.setContentView(R.layout.countdowntimer);
mmDialog1.setTitle("Stop-watch");
Button ddButton1 = (Button) mmDialog1.findViewById(R.id.countdown_exit);
final Button ddButton2 = (Button) mmDialog1.findViewById(R.id.countdown_start);
final TextView timeview = (TextView) mmDialog1.findViewById(R.id.timeview);
ddButton2.setTag(1);
ddButton2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
final int status = (Integer) v.getTag();
if (status == 1) {
ddButton2.setText("Stop");
countDownTimer = new CountDownTimer(60000, 1000) {
public void onTick(long millisUntilFinished) {
int time = (int) (millisUntilFinished/1000);
timeview.setText(Integer.toString(time));
}
#Override
public void onFinish() {
timeview.setText("60");
ddButton2.setText("Start");
MediaPlayer stop = MediaPlayer.create(context, R.raw.stop);
stop.start();
}
}.start();
v.setTag(0);
} else {
ddButton2.setText("Start");
timeview.setText("60");
countDownTimer.cancel();
v.setTag(1);
}
}
});
ddButton1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mmDialog1.dismiss();
}
});
mmDialog1.show();
}
});

My suggestion would be to implement an interface. When the dialog closes, have the callback shut off the media player.
A quick example is this.
interface
public interface DialogClosed {
void shutDownMediaPlayer();
}
then implement the interface in the calling activity
activity
public class MainActivity extends Activity implements DialogClosed {
....
#Override
public void shutDownMediaPlayer() {
//shut down media player here
}
}
Also, you may add a boolean to check if the dialog is showing like this
boolean isShowing = mDialog.isShowing();
and then you can just shut off the media player at any point if this is false.

So I've used some pointers from Jawascript and also edited my code a little, now it works:
stopwatch1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
final Dialog mmDialog1 = new Dialog(context);
mmDialog1.setContentView(R.layout.countdowntimer);
mmDialog1.setTitle("Stop-watch");
Button ddButton1 = (Button) mmDialog1.findViewById(R.id.countdown_exit);
final Button ddButton2 = (Button) mmDialog1.findViewById(R.id.countdown_start);
final TextView timeview = (TextView) mmDialog1.findViewById(R.id.timeview);
final MediaPlayer stop = MediaPlayer.create(context, R.raw.stop);
ddButton2.setTag(1);
mmDialog1.setCancelable(false);
if (mmDialog1.isShowing() == false) {
stop.stop();
}
ddButton2.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
final int status = (Integer) v.getTag();
if (status == 1) {
ddButton2.setText("Stop");
countDownTimer = new CountDownTimer(60000, 1000) {
public void onTick(long millisUntilFinished) {
int time = (int) (millisUntilFinished/1000);
timeview.setText(Integer.toString(time));
}
#Override
public void onFinish() {
timeview.setText("60");
ddButton2.setText("Start");
try {
stop.prepare();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
stop.start();
}
}.start();
v.setTag(0);
} else {
ddButton2.setText("Start");
timeview.setText("60");
countDownTimer.cancel();
v.setTag(1);
stop.stop();
}
}
});
ddButton1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mmDialog1.dismiss();
}
});
mmDialog1.show();
}
});

cancel countdowntimer on onbackpressed

I'm trying to cancel the countdowntimer on onbackpressed, I put counter.cancel; there but "'count' cannot be resolved" error appears. I think It can't find the countdowntimer!
There is a btn_riazi1_1_1 that can cancel the timer.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_riazi1_1);
//// handling timer
final TextView textic = (TextView) findViewById(R.id.riazi1_1_timer);
final CountDownTimer Count = new CountDownTimer(5000, 1000) {
public void onTick(long millisUntilFinished) {
textic.setText(getResources().getString(R.string.remaintime) + millisUntilFinished / 1000);
}
public void onFinish() {
textic.setText(getResources().getString(R.string.timesup));
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
Intent i=new Intent(Riazi1_1.this,Riazi1_2.class);
startActivity(i);
}
}, 1000);
}
};
Count.start();
/////////////////
//// handling button1
Button btn1 = (Button) findViewById(R.id.btn_riazi1_1_1);
btn1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Count.cancel();
TextView txtwrong = (TextView) findViewById(R.id.txt_wrong_riazi1_1);
txtwrong.setVisibility(View.VISIBLE);
Button btn2 = (Button) findViewById(R.id.btn_riazi1_1_2);
btn2.setBackgroundColor(Color.GREEN);
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
Intent i=new Intent(Riazi1_1.this,Riazi1_2.class);
startActivity(i);
}
}, 1000);
}
});
}
#Override
public void onBackPressed(){
super.onBackPressed();
Count.cancel(); // error: Count cannot be resolved ///
}
}

You have declared the TImer within onCreate method. So you cannot access it outside of onCreate. Declare it as a member variable.
private CountDownTimer Count; /// declare it as a member variable
and in the onCreate method initialize it like
Count = new CountDownTimer(5000, 1000).....
[A suggestion, use the naming convension. naming a variable starting with capital letter is really confusing]

How do I stop a timer that hasn't finished and then start a new one?

I'm attempting to do a guessing game, of sorts. The issue is my timer bleeds into the next one after a question is answered (button pressed) and a new timer starts. This leads to two timers changing a textview at different intervals, which is not how it's supposed to be. I'd like to know how to stop my previous countdown and start a new one. Thanks! Here's my code:
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
final TextView textic = (TextView) findViewById(R.id.button1);
long total = 30000;
final CountDownTimer Count = new CountDownTimer(total, 1000) {
public void onTick(long millisUntilFinished) {
textic.setText("Time Left: " + millisUntilFinished / 1000);
}
public void onFinish() {
textic.setText("OUT OF TIME!");
finish();
}
};
Count.start();

Heven't tested the code but I would use something like this:
final TextView textic = (TextView) findViewById(R.id.button1);
final android.os.CountDownTimer Count = new android.os.CountDownTimer(total, 1000) {
public void onTick(long millisUntilFinished) {
textic.setText("Time Left: " + millisUntilFinished / 1000);
}
public void onFinish() {
textic.setText("OUT OF TIME!");
}
};
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Count.cancel();
Count.start();
}
});

finish CountDownTimer in On finish
#Override
public void onFinish() {
Log.v(TAG, "On Finish");
textvieew.setText("your text");
countDownTimer.cancel();
}

CountDownTimer issue

Basically my aim is to have this timer reset whenever the user presses button b. I've tried a few methods such as if( i==true && bIsPressed()) but no luck, any ideas?
//2 buttons
Button =b;
TextView = time;
//countdown code
CountDownTimer Count = new CountDownTimer(11000, 1000) {
public void onTick(long millisUntilFinished) {
time.setText(""+millisUntilFinished / 1000);
}
public void onFinish() {
time.setText("Finished");
}
}; Count.start();

Haven't tested it, but I would do something along the lines of:
private void setupTimerResetButton()
{
mTimerResetButton.setOnClickListener(new OnClickListener(){
public void onClick(){
resetTimer();
}
});
}
private void resetTimer()
{
if(mTimer != null){
mTimer.cancel();
mTimer = null;
}
mTimer = new CountDownTimer(11000, 1000) {
public void onTick(long millisUntilFinished) {
mTimerTextView.setText(""+millisUntilFinished / 1000);
}
public void onFinish() {
mTimerTextView.setText("Finished");
}
};
mTimer.start();
}