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)
...

Why does timer loop not initialize at initial value when it calls onFinish() method?

I want to build a 5 second timer that counts down to 0 in 1 second intervils and then resets to the initial value of 5 seconds. The timer needs to run continously. After looking at this thread,
Android - loop part of the code every 5 seconds
I used the CountDownTimer Class and called the start() method within the onFinish() method so that when the timer finished, it would reset to 5. It does run on a continous loop, however I notice that after the first loop, it either countsdown as 4-3-2-1-0 or 5-3-2-1-0.
Can somebody explain to me why this happens?
private long START_TIME_IN_MILLIS = 5000;
//set up our variables
private CountDownTimer timer;
private TextView textView;
private Button starttimer;
private long mTimeLeftInMillis = START_TIME_IN_MILLIS;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = findViewById(R.id.text_view_countdown);
starttimer = findViewById(R.id.button_start_pause);
//set onclik listener when touch imput button
starttimer.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
beginTime();
}
});
}
//creating my own method
private void beginTime() {
timer = new CountDownTimer(mTimeLeftInMillis, 1000) {
#Override
public void onTick(long millisUntilFinished) {
mTimeLeftInMillis = millisUntilFinished;
updateCountDownText();
}
#Override
public void onFinish() {
start();
}
}.start();
}
private void updateCountDownText(){
int minutes= (int) (mTimeLeftInMillis / 1000)/ 60;
int seconds= (int) (mTimeLeftInMillis / 1000) % 60;
String timeLeftFormatted = String.format(Locale.getDefault(),"%02d:%02d", minutes, seconds);
textView.setText(timeLeftFormatted);
}
}

Try this
#Override
public void onFinish() {
mTimeLeftInMillis = START_TIME_IN_MILLIS;
}

Custom Count Up Timer

I need a count up timer in my application. I browsed many forums about this subject, but I could not find anything. Actually I understood we can do this with chronometer, but I have 2 problem with chronometer:
I cannot using chronometer in Service because chronometer needs a layout.
I cannot initialize chronometer to count more than 1 hour.
My code is here:
stopWatch = new Chronometer (MainActivity.this);
startTime = SystemClock.elapsedRealtime();
stopWatch.start();
stopWatch.setOnChronometerTickListener(new Chronometer.OnChronometerTickListener() {
#Override
public void onChronometerTick(Chronometer arg0) {
countUp = (SystemClock.elapsedRealtime() - arg0.getBase()) / 1000;
String asText = (countUp / 60) + ":" + (countUp % 60);
Log.i("t", asText);
}
});

You can use a countDownTimer in reverse and get the time elapsed.
long totalSeconds = 30;
long intervalSeconds = 1;
CountDownTimer timer = new CountDownTimer(totalSeconds * 1000, intervalSeconds * 1000) {
public void onTick(long millisUntilFinished) {
Log.d("seconds elapsed: " , (totalSeconds * 1000 - millisUntilFinished) / 1000);
}
public void onFinish() {
Log.d( "done!", "Time's up!");
}
};
To start the timer.
timer.start();
To stop the timer.
timer.cancel();

The sec,min and hr increments everytime the values hit 59,59,23 respectively. Each values are displayed in different views creating a digital stopwatch.
checkin.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(final View view) {
checkin.setEnabled(false);
new CountDownTimer(300000000, 1000){
public void onTick(long millisUntilFinished){
sec++;
if(sec==59) {
min++;
sec=0;
}
if(min==59){
min=0;
hr++;
}
if(hr==23){
hr=00;
}
secView.setText(String.valueOf(sec));
minView.setText(String.valueOf(min));
hrView.setText(String.valueOf(hr));
}
public void onFinish(){
Snackbar.make(view, "Finish", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
}.start();
}
});

Using RxJava, you can write
Disposable var = Observable
.interval(1, TimeUnit.SECONDS)
.subscribe(
time -> {
long minutes = time / 60;
long second = time % 60;
timer.setText("" + minutes + ":" + second);
});
you can stop the timer by using
var.dispose()

You can use this code to do so:
https://gist.github.com/MiguelLavigne/8809180c5b8fe2fc7403
/**
* Simple timer class which count up until stopped.
* Inspired by {#link android.os.CountDownTimer}
*/
public abstract class CountUpTimer {
private final long interval;
private long base;
public CountUpTimer(long interval) {
this.interval = interval;
}
public void start() {
base = SystemClock.elapsedRealtime();
handler.sendMessage(handler.obtainMessage(MSG));
}
public void stop() {
handler.removeMessages(MSG);
}
public void reset() {
synchronized (this) {
base = SystemClock.elapsedRealtime();
}
}
abstract public void onTick(long elapsedTime);
private static final int MSG = 1;
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
synchronized (CountUpTimer.this) {
long elapsedTime = SystemClock.elapsedRealtime() - base;
onTick(elapsedTime);
sendMessageDelayed(obtainMessage(MSG), interval);
}
}
};
}

implementing countdown timer with user input

i am trying to implement a countdown timer that starts from the number that the user inputs in the EditText. When i am running my program with the emulator, i realise that something goes wrong inside the countdown timer block since it does not enter inside this block.
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final EditText countDownTxt = (EditText) findViewById(R.id.editText2);
final EditText intervalTxt = (EditText) findViewById(R.id.editText1);
findViewById(R.id.button1).setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
int interval = Integer.parseInt(intervalTxt.getText().toString());
Log.d("buttonpressed", "interval countdown equals " + interval);
new CountDownTimer(Integer.parseInt(intervalTxt.getText().toString()), 1000) {
public void onTick(final long millisUntilFinished) {
Log.d("counttimer1", "enter");
runOnUiThread(new Runnable() {
#Override
public void run() {
countDownTxt.setText("" + millisUntilFinished / 1000);
}
});
countDownTxt.setText(""+ millisUntilFinished / 1000);
}
public void onFinish() {
countDownTxt.setText("done!");
}
}.start();
}
}
);
Any suggestions on solving this problemt ?

try using this
long timeVal = Long.parseLong(intervalTxt.getText().toString());
new CountDownTimer(timeVal, 1000) {
}

If you want the entered number by user present seconds, you should have like:
int time = Integer.parseInt(intervalTxt.getText().toString()) * 1000;
new CountDownTimer(time, 1000) {
...

How can I pause the timer in android?

I have gone through the link http://dewful.com/?tag=basic-android-timer regarding the timer application in android. It is working fine. I need to add the pause button to stop the timer and a play button to start the timer again from where I stopped. Can I achieve that task?
My Code:
long timervalue = 50000;
CountDownTimer Counter1 = new CountDownTimer(timervalue, 1000)
{
public void onTick(final long millisUntilFinished)
{
time.setText(formatTime(millisUntilFinished));
pause.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Counter1.cancel();
}
}
);
resume.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Counter1.start();
timervalue = Long.parseLong(output);
System.out.println("paused timer value resumed"+timervalue);
Counter1.onTick(timervalue);
}
}
);
}
public void onFinish()
{
Counter1.cancel();
}
};
public String formatTime(long millis)
{
output = "00";
seconds = millis / 1000;
seconds = seconds % 60;
System.out.println("seconds here"+seconds);
String secondsD = String.valueOf(seconds);
System.out.println("secondsD here"+secondsD);
if (seconds <
10) secondsD = "0" + seconds;
System.out.println("secondsD here in if"+secondsD);
output = secondsD;
return output;
}
In the above code when resume button is clicked the timer is again starting from 50sec and I don't want like that. It should start from the time where I paused. Please help me regarding this...I am struggling for this since one week......
Will be really thankful for the help..........

public class TimerActivity extends Activity
{
EditText e1;
MyCount counter;
Long s1;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
e1=(EditText)findViewById(R.id.editText1);
counter= new MyCount(5000,1000);
counter.start();
}
public void asdf(View v)
{
switch(v.getId())
{
case R.id.button1: counter.cancel();
break;
case R.id.button2: counter= new MyCount(s1,1000);
counter.start();
}
}
public class MyCount extends CountDownTimer
{
public MyCount(long millisInFuture, long countDownInterval)
{
super(millisInFuture, countDownInterval);
}
#Override public void onFinish()
{
e1.setText("DONE");
}
#Override public void onTick(long millisUntilFinished)
{
s1=millisUntilFinished;
e1.setText("left:"+millisUntilFinished/1000);
}
}
}

public void time(long m){
timer=new CountDownTimer(m, 1000) {
public void onTick(long millisUntilFinished) {
tv_timer.setText(formatTime(millisUntilFinished));
}
public void onFinish() {
tv_timer.setText("done!");
}
}.start();
}
i have used this for timer and i have put button for pause and use this
case R.id.bT_PAUSE:
String s_time = null;
try{
if(Bt_pause.getText().equals("PAUSE")){
s_time=tv_timer.getText().toString();
timer.cancel();
String[] Pause_time=s_time.split(":");
m=Long.parseLong(Pause_time[0].trim());
n=Long.parseLong(Pause_time[1].trim());
m=(m*60)+n;
m=m*1000;
Bt_pause.setText("RESUME");
}else if(Bt_pause.getText().equals("RESUME")){
//min_longmillis=Long.parseLong(sss);
//min_longmillis=min_longmillis*1000*60;
//min_longmillis=m;
//timer.start();
Toast.makeText(this,String.valueOf(m),Toast.LENGTH_SHORT).show();
time(m);
Bt_pause.setText("PAUSE");
}
}catch(Exception e){
Toast.makeText(this,e.toString(),Toast.LENGTH_SHORT).show();
}
break;
and this for format time
public String formatTime(long millis) {
String output = "00:00";
long seconds = millis / 1000;
long minutes = seconds / 60;
seconds = seconds % 60;
minutes = minutes % 60;
String sec = String.valueOf(seconds);
String min = String.valueOf(minutes);
if (seconds < 10)
sec = "0" + seconds;
if (minutes < 10)
min= "0" + minutes;
output = min + " : " + sec;
return output;
}//formatTime