Android Studio CountDownTimer 不工作

Question

我目前正在开发一个简单的测验应用程序，我尝试使用一个计时器，它只允许您在 10 秒内回答问题，然后再转到下一个问题。虽然，计时器没有按我想要的方式工作。大约 5 秒后问题发生变化，但应用程序甚至没有显示它，它一直停留在 10，如下所示：

这是 QuestionActivity class:

的代码

package com.example.myquiz;

import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import android.animation.Animator;
import android.content.Intent;
import android.content.res.ColorStateList;
import android.graphics.Color;
import android.os.Build;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.os.Handler;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.DecelerateInterpolator;
import android.widget.Button;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

@RequiresApi(api = Build.VERSION_CODES.O)
public class QuestionActivity extends AppCompatActivity implements View.OnClickListener {

    private TextView question, qCount, timer;
    private Button option1, option2, option3, option4;
    private List<Question> questionList;
    private int quesNum;
    private CountDownTimer countDown;
    private int score;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_question);

        question = findViewById(R.id.question);
        qCount = findViewById(R.id.quest_num);
        timer = findViewById(R.id.countdown);

        option1 = findViewById(R.id.option1);
        option2 = findViewById(R.id.option2);
        option3 = findViewById(R.id.option3);
        option4 = findViewById(R.id.option4);

        option1.setOnClickListener(this);
        option2.setOnClickListener(this);
        option3.setOnClickListener(this);
        option4.setOnClickListener(this);

        getQuestionsList();

        score = 0;


    }

    private void getQuestionsList() {
        questionList = new ArrayList<>();

        questionList.add(new Question("Question1", "A", "B", "C", "D", 2));
        questionList.add(new Question("Question2", "B", "B", "D", "A", 2));
        questionList.add(new Question("Question3", "C", "B", "A", "D", 2));
        questionList.add(new Question("Question4", "A", "D", "C", "B", 2));
        questionList.add(new Question("Question5", "C", "D", "A", "D", 2));

        setQuestion();
    }

    private void setQuestion() {
        timer.setText(String.valueOf(10));

        question.setText(questionList.get(0).getQuestion());
        option1.setText(questionList.get(0).getOptionA());
        option2.setText(questionList.get(0).getOptionB());
        option3.setText(questionList.get(0).getOptionC());
        option4.setText(questionList.get(0).getOptionD());

        qCount.setText(String.valueOf(1) + "/" + String.valueOf(questionList.size()));

        startTimer();

        quesNum = 0;

    }

    private void startTimer() {
        countDown = new CountDownTimer(12000, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                if (millisUntilFinished < 10)

                    timer.setText(String.valueOf(millisUntilFinished/1000));


            }

            @Override
            public void onFinish() {
                changeQuestion();

            }
        };

        countDown.start();
    }


    @Override
    public void onClick(View v) {
        int selectedOption = 0;
        switch (v.getId()) {
            case R.id.option1:
                selectedOption = 1;
                break;

            case R.id.option2:
                selectedOption = 2;
                break;

            case R.id.option3:
                selectedOption = 3;
                break;

            case R.id.option4:
                selectedOption = 4;
                break;

            default:


        }
        countDown.cancel();
        checkAnswer(selectedOption, v);
    }

    private void checkAnswer(int selectedOption, View view) {
        if (selectedOption == questionList.get(quesNum).getCorrectAns()) {

            //Right Answer
            ((Button) view).setBackgroundTintList(ColorStateList.valueOf(Color.GREEN));
            score++;

        } else {

            //Wrong Answer
            ((Button) view).setBackgroundTintList(ColorStateList.valueOf(Color.RED));

            switch (questionList.get(quesNum).getCorrectAns()) {
                case 1:
                    option1.setBackgroundTintList(ColorStateList.valueOf(Color.GREEN));
                    break;
                case 2:
                    option2.setBackgroundTintList(ColorStateList.valueOf(Color.GREEN));
                    break;
                case 3:
                    option3.setBackgroundTintList(ColorStateList.valueOf(Color.GREEN));
                    break;
                case 4:
                    option4.setBackgroundTintList(ColorStateList.valueOf(Color.GREEN));
                    break;
            }

        }
        Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                changeQuestion();
            }
        }, 2000);


    }

    private void changeQuestion() {
        if (quesNum < questionList.size() - 1) {
            quesNum++;

            playAnim(question, 0, 0);
            playAnim(option1, 0, 1);
            playAnim(option2, 0, 2);
            playAnim(option3, 0, 3);
            playAnim(option4, 0, 4);

            qCount.setText(String.valueOf(quesNum + 1) + "/" + String.valueOf(questionList.size()));

            timer.setText(String.valueOf(10));
            startTimer();


        } else {
            //Go to Score Activity
            Intent intent = new Intent(QuestionActivity.this, ScoreActivity.class);
            intent.putExtra("SCORE",String.valueOf(score) + "/" + String.valueOf(questionList.size()));
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
            startActivity(intent);
            QuestionActivity.this.finish();
        }
    }

    private void playAnim(View view, final int value, int viewNum) {
        view.animate().alpha(value).scaleX(value).scaleY(value).setDuration(500).setStartDelay(100).setInterpolator(new DecelerateInterpolator()).setListener(new Animator.AnimatorListener() {
            @Override
            public void onAnimationStart(Animator animation) {

            }

            @Override
            public void onAnimationEnd(Animator animation) {
                if (value == 0) {
                    switch (viewNum) {
                        case 0:
                            ((TextView) view).setText(questionList.get(quesNum).getQuestion());
                            break;
                        case 1:
                            ((Button) view).setText(questionList.get(quesNum).getOptionA());
                            break;
                        case 2:
                            ((Button) view).setText(questionList.get(quesNum).getOptionB());
                            break;
                        case 3:
                            ((Button) view).setText(questionList.get(quesNum).getOptionC());
                            break;
                        case 4:
                            ((Button) view).setText(questionList.get(quesNum).getOptionD());
                            break;
                    }

                    if (viewNum != 0)
                        ((Button) view).setBackgroundTintList(ColorStateList.valueOf(Color.parseColor("#e8c1e1")));

                    playAnim(view, 1, viewNum);
                }
            }

            @Override
            public void onAnimationCancel(Animator animation) {

            }

            @Override
            public void onAnimationRepeat(Animator animation) {

            }
        });
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();

        countDown.cancel();
    }
}

我该如何解决？

Answer 1

您的 onTick 有一个问题 - 我假设您希望它在倒计时到 1（而不是显示 0）时更新文本。目前的编写方式永远不会（很少）更新计时器文本。

（您可能希望将持续时间更改为 500 - 原因是我已经 posted 您可能永远不会看到“9”（计时器实现方式的副作用） - 更频繁地更新只是意味着在某些情况下它将更新为相同的文本。）

这可能无法解决您提到的所有问题，但这应该有所帮助 - post 进行此更新后的任何遗留问题：

private void startTimer() {
    // stop timer 10 seconds in future - provide updates after 1s and every 1s until
    // complete.  Change the 1000 (in constructor) to 500 for more consistent UI update results.

    countDown = new CountDownTimer(10000, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            // milliseconds (1000 in 1 sec) - update text if at least 1s remaining.
            if (millisUntilFinished > 1000) {

                timer.setText(String.valueOf(millisUntilFinished/1000));
            }

        }

        @Override
        public void onFinish() {
            changeQuestion();

        }
    };

    countDown.start();
}

此展示了对 10 秒计时器的粗略期望，以便更好地理解其行为。

Answer 2

您尝试过使用 AsyncTask 吗？

    public class TareaInternet extends AsyncTask<String, Float, String>

它通常解决定时器的问题。

Answer 3

the app doesn't even show it, it stays stuck on 10

在 changeQuestion() 中，也许将参数从 10 更改为 0 会得到您需要的。

 timer.setText(String.valueOf(0));

Android Studio CountDownTimer 不工作

Android Studio CountDownTimer not working

java

android

countdowntimer

android-studio