CountDownTimer cancel() 不会取消计时器并继续工作

Question

我正在使用 CountDownTimer class 更新 firebase 实时数据库，但 cancel() 方法似乎不起作用。

我想在计时器结束时调用 fetchUserPoints() 并自己添加点。

你能帮帮我吗？

int time = 6;
private CountDownTimer countDownTimer;


private void timeDownTimer() {
        countDownTimer = new CountDownTimer(6000, 1000) {

            public void onTick(long millisUntilFinished) {
                tvTimer.setText("0:" + checkDigit(time));
                time--;

            }

            public void onFinish() {
                tvTimer.setText("Time finished");
                fechUserPoints();
            }


        }.start();
    }

    public String checkDigit(int number) {
        return number <= 9 ? "0" + number : String.valueOf(number);
    }

    private void fetchUserPoints() {
        countDownTimer.cancel();
        reference.child(mId).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                prevPoints = dataSnapshot.child("points").getValue().toString();
                int prePoints = Integer.valueOf(prevPoints);
                String newPoints = String.valueOf(prePoints + ADDED_POINTS);

                reference.child(mId).child("points").setValue(newPoints).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        Toast.makeText(getContext(), "Process is successful", Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

这里 fetchUserPoints() 继续调用。

Answer 1

尝试将 CountDownTimer 维护为方法局部变量而不是 global/class 级别变量，因为如果触发timeDownTimer() 多次然后 countDownTimer[=20= 的旧引用] 将会丢失，您将无法取消之前启动的计时器。

我认为这可能是个问题。

Answer 2

您可以在 onFinish 方法中取消您的 CountDownTimer。试试这个

int time = 6;
private CountDownTimer countDownTimer;


private void timeDownTimer() {
        countDownTimer = new CountDownTimer(6000, 1000) {

            public void onTick(long millisUntilFinished) {
                tvTimer.setText("0:" + checkDigit(time));
                time--;

            }

            public void onFinish() {
                tvTimer.setText("Time finished");
                countDownTimer.cancel();
                fechUserPoints();
            }


        }.start();
    }

    public String checkDigit(int number) {
        return number <= 9 ? "0" + number : String.valueOf(number);
    }

    private void fetchUserPoints() {

        reference.child(mId).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                prevPoints = dataSnapshot.child("points").getValue().toString();
                int prePoints = Integer.valueOf(prevPoints);
                String newPoints = String.valueOf(prePoints + ADDED_POINTS);

                reference.child(mId).child("points").setValue(newPoints).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        Toast.makeText(getContext(), "Process is successful", Toast.LENGTH_SHORT).show();
                    }
                });
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
    }

另一个例子在这里看到它工作

private CountDownTimer countDownTimer;
    int time = 6;

    private void timeDownTimer() {
        countDownTimer = new CountDownTimer(6000, 1000) {

            public void onTick(long millisUntilFinished) {
                Log.e("TIK : " , checkDigit(time));
                time--;

            }

            public void onFinish() {
                countDownTimer.cancel();
                test();
            }


        }.start();
    }

    public String checkDigit(int number) {
        return number <= 9 ? "0" + number : String.valueOf(number);
    }

    private void test(){
        Log.e("TIK : " , "inside my method");
        Toast.makeText(this,"on finish",Toast.LENGTH_LONG).show();
    }

Answer 3

您不需要在 fetchUserPoints() 中调用 countDownTimer.cancel() 因为您调用了 fetchUserPoints() 在 onFinish 方法中 countDownTimer;您正在尝试取消已结束的进程。

CountDownTimer cancel() 不会取消计时器并继续工作

CountDownTimer cancel() doesn't cancel the timer and continue working

java

android

countdowntimer

firebase

firebase-realtime-database