CountdownTimer add time to the current time

CountdownTimer add time to the current time

I have a countdown timer and I want to add 10 seconds to it whenever my
isAddTime method is true. I have successfully added it but whenever the
time is added, it still finishes on the current time.
For example, when it is 20 sec and then isAddTime hits true, the time will
be 30 sec but it will end still end in 20 seconds.
Here's my code:
timerHolder = new CountDownTimer(30000, 1000) {
@Override
public void onFinish() {
Class.isAddTime = false;
Intent i = new Intent(getBaseContext(), OtherClass.class);
startActivity(i);
}
@Override
public void onTick(long millisUntilFinished) {
timeLeft = millisUntilFinished;
if(Class.isAddTime()){
timerHolder.cancel();
AddTime();
Class.isAddTime = false;
}
timer.setText("Time left: " + String.valueOf(timeLeft /
1000));
}
}.start();
And here is the AddTime():
private void AddTime(){
timerHolder = new CountDownTimer(timeLeft + 10000, 1000) {
@Override
public void onFinish() {
Class.isAddTime = false;
Intent i = new Intent(getBaseContext(), OtherClass.class);
startActivity(i);
}
@Override
public void onTick(long millisUntilFinished) {
timeLeft += 10000;
timeLeft = millisUntilFinished;
if(Class.isAddTime()){
timerHolder.cancel();
AddTime();
Class.isAddTime = false;
}
timer.setText("Time left: " + String.valueOf(timeLeft / 1000));
}
}.start();
I was wondering why it still continue the current time even if i had it
cancelled?