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如何在Activity中正确设置CountDownTimer

[英]How to Correctly set CountDownTimer in Activity

 原文  2016-08-30 18:32:02  5   1    java/ android/ android-activity

问题描述

Please help, I have a countdowntimer within a method that I need to pause and resume. 请帮助，我在一个方法中有一个倒计时器，我需要暂停和恢复。 I managed to pause the timer by using the .cancel() in the onPause however I cannot get it to restart properly. 我设法通过使用onPause中的.cancel（）来暂停计时器但是我无法正常重启。 I have 2 scenarios: Scenario 1- It pauses but when restarting it seems to restart both countdown timers even if the initial timer was cancelled. 我有2个场景：场景1-它暂停，但重新启动时，即使初始计时器被取消，它似乎也会重启两个倒计时器。 

    public void playAgain (View view) {

        score = 0;
        numberOfQuestions = 0;
        timerTextView.setText("60s");
        pointsTextView.setText("0/0");
        resultTextView.setText("");
        playAgainButton.setVisibility(View.INVISIBLE);
        returnToMenu.setVisibility(View.INVISIBLE);
        resultDisplayTextView.setVisibility(View.INVISIBLE);
        countDownText.setVisibility(View.VISIBLE);
        button0.setVisibility(View.INVISIBLE);
        button1.setVisibility(View.INVISIBLE);
        button2.setVisibility(View.INVISIBLE);
        button3.setVisibility(View.INVISIBLE);
        sumTextView.setVisibility(View.INVISIBLE);

            countDownTimer = new CountDownTimer(millisInFuture, countDownInterval) {
                @Override
                public void onTick(long timeRemain) {

                    millisInFuture = timeRemain;

                    countDownText.setText(String.valueOf(timeRemain / 1000 - 60));

                    if (timeRemain <= 61000) {

                        timerTextView.setText(String.valueOf(timeRemain / 1000) + "s");
                        button0.setEnabled(true);
                        button1.setEnabled(true);
                        button2.setEnabled(true);
                        button3.setEnabled(true);
                        button0.setVisibility(View.VISIBLE);
                        button1.setVisibility(View.VISIBLE);
                        button2.setVisibility(View.VISIBLE);
                        button3.setVisibility(View.VISIBLE);
                        sumTextView.setVisibility(View.VISIBLE);
                        countDownText.setVisibility(View.INVISIBLE);
                    }

                }


                @Override
                public void onFinish() {

                    timerTextView.setText("0s");



                    if (score > 0) {
                        percentage = score * 100 / numberOfQuestions;
                    } else {
                        percentage = 0;
                    }

                    button0.setEnabled(false);
                    button1.setEnabled(false);
                    button2.setEnabled(false);
                    button3.setEnabled(false);
                    playAgainButton.setVisibility(View.VISIBLE);
                    returnToMenu.setVisibility(View.VISIBLE);
                    resultDisplayTextView.setVisibility(View.VISIBLE);
                    resultTextView.setText(" ");
    }
            }.start();

        generateQuestion();

    }


 @Override
    public void onPause() {

        countDownTimer.cancel();

        super.onPause();
    }

    @Override
    public void onResume() {
        super.onResume();
CountDownTimer countDownTimer1 = new CountDownTimer(millisInFuture, countDownInterval) {
            @Override
            public void onTick(long timeRemain) {

                millisInFuture = timeRemain;

                countDownText.setText(String.valueOf(timeRemain / 1000 - 60));

                if (timeRemain <= 61000) {

                    timerTextView.setText(String.valueOf(timeRemain / 1000) + "s");
                    button0.setEnabled(true);
                    button1.setEnabled(true);
                    button2.setEnabled(true);
                    button3.setEnabled(true);
                    button0.setVisibility(View.VISIBLE);
                    button1.setVisibility(View.VISIBLE);
                    button2.setVisibility(View.VISIBLE);
                    button3.setVisibility(View.VISIBLE);
                    sumTextView.setVisibility(View.VISIBLE);
                    countDownText.setVisibility(View.INVISIBLE);
                }

            }


            @Override
            public void onFinish() {

                timerTextView.setText("0s");



                if (score > 0) {
                    percentage = score * 100 / numberOfQuestions;
                } else {
                    percentage = 0;
                }

                button0.setEnabled(false);
                button1.setEnabled(false);
                button2.setEnabled(false);
                button3.setEnabled(false);
                playAgainButton.setVisibility(View.VISIBLE);
                returnToMenu.setVisibility(View.VISIBLE);
                resultDisplayTextView.setVisibility(View.VISIBLE);
                resultTextView.setText(" ");
}
        }.start();
}

The second scenario just crashes the system: 第二种情况只是崩溃了系统： 

    public void playAgain (View view) {

        score = 0;
        numberOfQuestions = 0;
        timerTextView.setText("60s");
        pointsTextView.setText("0/0");
        resultTextView.setText("");
        playAgainButton.setVisibility(View.INVISIBLE);
        returnToMenu.setVisibility(View.INVISIBLE);
        resultDisplayTextView.setVisibility(View.INVISIBLE);
        countDownText.setVisibility(View.VISIBLE);
        button0.setVisibility(View.INVISIBLE);
        button1.setVisibility(View.INVISIBLE);
        button2.setVisibility(View.INVISIBLE);
        button3.setVisibility(View.INVISIBLE);
        sumTextView.setVisibility(View.INVISIBLE);

            countDownTimer = new CountDownTimer(millisInFuture, countDownInterval) {
                @Override
                public void onTick(long timeRemain) {

                    millisInFuture = timeRemain;

                    countDownText.setText(String.valueOf(timeRemain / 1000 - 60));

                    if (timeRemain <= 61000) {

                        timerTextView.setText(String.valueOf(timeRemain / 1000) + "s");
                        button0.setEnabled(true);
                        button1.setEnabled(true);
                        button2.setEnabled(true);
                        button3.setEnabled(true);
                        button0.setVisibility(View.VISIBLE);
                        button1.setVisibility(View.VISIBLE);
                        button2.setVisibility(View.VISIBLE);
                        button3.setVisibility(View.VISIBLE);
                        sumTextView.setVisibility(View.VISIBLE);
                        countDownText.setVisibility(View.INVISIBLE);
                    }

                }


                @Override
                public void onFinish() {

                    timerTextView.setText("0s");



                    if (score > 0) {
                        percentage = score * 100 / numberOfQuestions;
                    } else {
                        percentage = 0;
                    }

                    button0.setEnabled(false);
                    button1.setEnabled(false);
                    button2.setEnabled(false);
                    button3.setEnabled(false);
                    playAgainButton.setVisibility(View.VISIBLE);
                    returnToMenu.setVisibility(View.VISIBLE);
                    resultDisplayTextView.setVisibility(View.VISIBLE);
                    resultTextView.setText(" ");
    }
            }.start();

        generateQuestion();

    }


 @Override
    public void onPause() {

        countDownTimer.cancel();

        super.onPause();
    }

    @Override
    public void onResume() {
        super.onResume();
countDownTimer.start();
}

I have googled and cannot seem to find a working solution. 我用谷歌搜索，似乎无法找到一个有效的解决方案。 Please help, Galaxy store refuses to upload my apk unless this feature works. 请帮助，Galaxy商店拒绝上传我的apk，除非此功能有效。

1 个解决方案

解决方案1
 3 已采纳  2016-08-30 19:48:53

The thing is, CountDownTimer is a relatively limited class. 问题是，CountDownTimer是一个相对有限的类。 It only has two methods, start() and cancel() , and two callbacks, onTick() and onFinish() . 它只有两个方法， start()和cancel() ，以及两个回调， onTick()和onFinish() 。 There is no pause/resume functionality built in. 内置暂停/恢复功能。

I set up a very basic Activity with a TextView to visualize the CountDownTimer's behavior, and it is working like you want - pausing when leaving activity, and resuming when you return. 我使用TextView设置了一个非常基本的Activity来可视化CountDownTimer的行为，它可以像你想要的那样工作 - 在离开活动时暂停，在你返回时恢复。 I've posted the simple code here: 我在这里发布了简单的代码： 

import android.os.CountDownTimer;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;

import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private TextView mTextView;
    private CountDownTimer mCountDownTimer;

    private static final long INTERVAL = 1000L;
    private long timeRemaining = 60000L;

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

        mTextView = (TextView)findViewById(R.id.text_view);
    }

    @Override
    protected void onResume() {
        super.onResume();

        mCountDownTimer = new CountDownTimer(timeRemaining, INTERVAL) {
            @Override
            public void onTick(long l) {
                mTextView.setText(String.format(Locale.getDefault(), "%d sec.", l / 1000L));
                timeRemaining = l;
            }

            @Override
            public void onFinish() {
                mTextView.setText("Done.");
            }
        };
        mCountDownTimer.start();
    }

    @Override
    protected void onPause() {
        super.onPause();
        mCountDownTimer.cancel();
    }
}

I'd start with checking if you can get this code to run, and then integrate the basic idea into your project. 我首先检查您是否可以运行此代码，然后将基本想法集成到您的项目中。 You essentially have to maintain the time remaining outside of the CountDownTimer object. 您基本上必须保持CountDownTimer对象之外的剩余时间。

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