java - 我该如何修复此代码，以便我的 android textview 使用倒计时器更新并显示剩余的秒数？

Question

我正在尝试制作电影倒计时中的倒计时应用程序。我对编码很陌生。这里的目标是更新显示剩余生存秒数的 TextView 。这是我为实现这一目标而编写的 java 代码。我知道其他方面比如年、日、时、分还没有完成。

import android.os.Bundle;
import android.os.CountDownTimer;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import java.util.Calendar;

public class MainActivity extends AppCompatActivity {
    private TextView mTextViewCountDownYears;
    private TextView mTextViewCountDownDays;
    private TextView mTextViewCountDownHours;
    private TextView mTextViewCountDownMinutes;
    private TextView mTextViewCountDownSeconds;

    private Button mButtonAccept;

    private CountDownTimer mCountDownTimer;

    private Boolean mTimerRunning;

    long timeLeftToLive = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Calendar deathDay = Calendar.getInstance();
        deathDay.set(2021,7,24,10,14,45);
        Calendar today = Calendar.getInstance();

        long diff = deathDay.getTimeInMillis() - today.getTimeInMillis();
        timeLeftToLive = diff;

        mTextViewCountDownYears = findViewById(R.id.text_view_countdown_years);
        mTextViewCountDownDays = findViewById(R.id.text_view_countdown_days);
        mTextViewCountDownHours = findViewById(R.id.text_view_countdown_hours);
        mTextViewCountDownMinutes = findViewById(R.id.text_view_countdown_minutes);
        mTextViewCountDownSeconds = findViewById(R.id.text_view_countdown_seconds);

        mButtonAccept = findViewById(R.id.button_accept);

        mButtonAccept.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startTimer();
            }
        });
    }
    private void startTimer(){
        mCountDownTimer = new CountDownTimer(timeLeftToLive, 1000) {
            @Override
            public void onTick(long millisUntilFinished) {
                timeLeftToLive = millisUntilFinished;
                updateTextView();
            }

            @Override
            public void onFinish() {

            }
        };
    }
    private void updateTextView() {
        long secondsLeft = timeLeftToLive / 1000;

        String secondsLeftFormatted = String.format("%02d",secondsLeft);

        mTextViewCountDownSeconds.setText(secondsLeftFormatted);
    }
}

Answer 1

你的代码看起来不错，而且你已经很接近它正常工作了!您只需在 startTimer() 函数内的 CountDownTimer 定义末尾添加一个 .start() 即可(在半函数之前)冒号)。像这样:

private void startTimer(){
    mCountDownTimer = new CountDownTimer(timeLeftToLive, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            timeLeftToLive = millisUntilFinished;
            updateTextView();
        }

        @Override
        public void onFinish() {

        }
    }.start();
}

有一个很好的例子供您引用here如果你需要的话