英文:
Change text from a class out
问题
I created a simple Java class. This should spend the time. With System.out.println it works too! But how can I inform a certain TextView that it should also change?
Countdown_Test.java
public class Countdown_test {private static long START_TIME_IN_MILLIS;private CountDownTimer mCountDownTimer;private boolean mTimerRunning;private long mTimeLeftInMillis;//private TextView timer;public Countdown_test(long start_time) {START_TIME_IN_MILLIS = start_time;mTimeLeftInMillis = START_TIME_IN_MILLIS;//timer = findViewById(R.id.timer); doesn't work}public void startTimer() {mCountDownTimer = new CountDownTimer(mTimeLeftInMillis, 1000) {@Overridepublic void onTick(long millisUntilFinished) {mTimeLeftInMillis = millisUntilFinished;updateCountDownText();}@Overridepublic void onFinish() {mTimerRunning = false;}}.start();mTimerRunning = true;}public void updateCountDownText() {int minutes = (int) (mTimeLeftInMillis / 1000) / 60;int seconds = (int) (mTimeLeftInMillis / 1000) % 60;String timeLeftFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);System.out.println(timeLeftFormatted);}}
MainActivity.java
Countdown_test ct = new Countdown_test(600000);button_start.setOnClickListener(v -> {ct.startTimer();});ct.updateCountDownText();
英文:
I created a simple Java class. This should spend the time. With System.out.println it works too! But how can I inform a certain TextView that it should also change?
Countdown_Test.java
public class Countdown_test {private static long START_TIME_IN_MILLIS;private CountDownTimer mCountDownTimer;private boolean mTimerRunning;private long mTimeLeftInMillis;//private TextView timer;public Countdown_test(long start_time) {START_TIME_IN_MILLIS = start_time;mTimeLeftInMillis = START_TIME_IN_MILLIS;//timer = findViewById(R.id.timer); dosen't work}public void startTimer() {mCountDownTimer = new CountDownTimer(mTimeLeftInMillis, 1000) {@Overridepublic void onTick(long millisUntilFinished) {mTimeLeftInMillis = millisUntilFinished;updateCountDownText();}@Overridepublic void onFinish() {mTimerRunning = false;}}.start();mTimerRunning = true;}public void updateCountDownText() {int minutes = (int) (mTimeLeftInMillis / 1000) / 60;int seconds = (int) (mTimeLeftInMillis / 1000) % 60;String timeLeftFormatted = String.format(Locale.getDefault(), "%02d:%02d", minutes, seconds);System.out.println(timeLeftFormatted);}}
MainActivity.java
Countdown_test ct = new Countdown_test(600000);button_start.setOnClickListener(v -> {ct.startTimer();});ct.updateCountDownText();
答案1
得分: 0
你可以编写一个接口，一个带有方法onTimeLeftChanged(String timeleft)的TimeLeftListener。然后，你的活动继承TimeLeftListener并实现onTimeLeftChanged()方法。
这是你更新视图的地方。
当你初始化CountDownTest时，可以像这样传递活动：
Countdown_test ct = new Countdown_test(600000, this);
并在你的CountDownTest类中创建一个监听器，像这样：
myTimeLeftListener = (TimeLeftListener) activity;
然后在你的updateCountDownText()方法中，你可以添加：
myTimeLeftListener.onTimeLeftChanged(timeleft);
你也可以使用ViewModel和LiveData。
英文:
You could write an interface, a TimeLeftListener with a method onTimeLeftChanged(String timeleft). Then your activity extends TimeLeftListener and implements the onTimeLeftChanged()-method.
This is where you update your views.
When you initiate your CountDownTest you pass the activity like this.
Countdown_test ct = new Countdown_test(600000, this);
And create al listener in you CountDownTest-class like this
myTimeLeftListener =(TimeleftListener)activity;
Then in your updateCountDownText()-Method you put
myTimeLeftListener.onTimeLeftChanged(timeleft)
You could also use ViewModel and LiveData.
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