Question

我已经为片段活动中的每个RecyclerView项目实施了倒计时器。倒计时器显示到期时间。倒计时器工作正常，但向上滚动时会开始闪烁。搜索了很多，但没有得到很好的参考。任何人都可以帮助我吗？

这是我的RecyclerView适配器

public class MyOfferAdapter extends RecyclerView.Adapter<MyOfferAdapter.FeedViewHolder>{
private final Context mContext;
private final LayoutInflater mLayoutInflater;
private ArrayList<Transactions> mItems = new ArrayList<>();
private ImageLoader mImageLoader;
private String imageURL;
private View mView;
private String mUserEmail;

public MyOfferAdapter(Context context) {
    mContext = context;
    mLayoutInflater = LayoutInflater.from(context);
    VolleySingleton mVolley = VolleySingleton.getInstance(mContext);
    mImageLoader = mVolley.getImageLoader();
}


public void addItems(ArrayList<Transactions> items,String userEmail) {
    int count = mItems.size();
    mItems.addAll(items);
    mUserEmail = userEmail;
    notifyItemRangeChanged(count, items.size());
}


@Override
public FeedViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    mView = mLayoutInflater.inflate(R.layout.my_feed_item_layout, parent, false);
    return new FeedViewHolder(mView);
}

@Override
public void onBindViewHolder(final FeedViewHolder holder, final int position) {
    holder.desc.setText(mItems.get(position).getDescription());//replace by title
    holder.scratchDes.setText(mItems.get(position).getScratchDescription());

    long timer = mItems.get(position).getTimerExpiryTimeStamp();
    Date today = new Date();
    final long currentTime = today.getTime();
    long expiryTime = timer - currentTime;


    new CountDownTimer(expiryTime, 500) {
        public void onTick(long millisUntilFinished) {
            long seconds = millisUntilFinished / 1000;
            long minutes = seconds / 60;
            long hours = minutes / 60;
            long days = hours / 24;
            String time = days+" "+"days" +" :" +hours % 24 + ":" + minutes % 60 + ":" + seconds % 60;
            holder.timerValueTimeStamp.setText(time);
        }

        public void onFinish() {
            holder.timerValueTimeStamp.setText("Time up!");
        }
    }.start();

}

@Override
public int getItemCount() {
    return mItems.size();
}

public static class FeedViewHolder extends RecyclerView.ViewHolder {
    TextView desc;
    TextView scratchDes;
    TextView timerValueTimeStamp;
    ImageView feedImage;
    CardView mCv;

    public FeedViewHolder(View itemView) {
        super(itemView);
        mCv = (CardView) itemView.findViewById(R.id.cv_fil);
        desc = (TextView) itemView.findViewById(R.id.desc_tv_fil);
        feedImage = (ImageView) itemView.findViewById(R.id.feed_iv_fil);
        scratchDes = (TextView) itemView.findViewById(R.id.tv_scratch_description);
        timerValueTimeStamp = (TextView) itemView.findViewById(R.id.tv_timer_value_time_stamp);

    }

}

这是我在适配器中使用的xml文件

<LinearLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<android.support.v7.widget.CardView     xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/cv_fil"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="@dimen/card_margin"
    android:layout_gravity="center"
    app:cardUseCompatPadding="true"
    app:cardElevation="4dp"
    android:elevation="6dp">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/feed_iv_fil"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:layout_alignParentTop="true"
            android:scaleType="fitXY"
            android:tint="@color/grey_tint_color" />

        <TextView
            android:id="@+id/tv_scratch_description"
            style="@style/ListItemText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="casul shoes"
            android:fontFamily="sans-serif-light"
            android:padding="10dp" />


        <TextView
            android:id="@+id/tv_timer_value_time_stamp"
            style="@style/CardTitle"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            />

        <TextView
            android:id="@+id/desc_tv_fil"
            style="@style/VendorNameText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/feed_iv_fil"
            android:textColor="#3f3e3f"
            android:padding="10dp"
            />

    </RelativeLayout>


</android.support.v7.widget.CardView>

这是我的RecyclerView的屏幕截图

Answer 1

这个问题很简单。

RecyclerView重用持有者，每次调用bind来更新其中的数据。

由于每次绑定任何数据时都会创建CountDownTimer，因此最终会有多个计时器更新相同的ViewHolder。

这里最好的方法是移动CountDownTimer中的FeedViewHolder作为参考，在绑定数据（如果启动）之前取消它并重新安排到所需的持续时间。

public void onBindViewHolder(final FeedViewHolder holder, final int position) {
    ...
    if (holder.timer != null) {
        holder.timer.cancel();
    }
    holder.timer = new CountDownTimer(expiryTime, 500) {
        ...
    }.start();
}

public static class FeedViewHolder extends RecyclerView.ViewHolder {
    ...
    CountDownTimer timer;

    public FeedViewHolder(View itemView) {
        ...
    }
}

这样，您将在启动另一个计时器之前取消该ViewHolder的任何当前计时器实例。

Answer 2

正如Andrei Lupsa所说，您应该在ViewHolder中保留CountDownTimer引用，如果您不想在滚动时（onBindViewHolder）重置计时器，则应检查onBindViewHolder中CountDownTimer引用是否为空：

public void onBindViewHolder(final FeedViewHolder holder, final int position) {

      ...

      if (holder.timer == null) {
          holder.timer = new CountDownTimer(expiryTime, 500) {

          ...

          }.start();   
      }
}


public static class FeedViewHolder extends RecyclerView.ViewHolder {

       ...

       CountDownTimer timer;

       public FeedViewHolder(View itemView) {

          .... 
  }
}

Answer 3

我可以想到两种类型的解决方案，它们没有使用CountDownTimer类

使用postDelayed方法处理并在其中调用notifyDataSetChanged()。在您的适配器中进行计时计算。像下面的代码。

在适配器类的构造方法中

final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
    @Override
    public void run() {
        notifyDataSetChanged();
        handler.postDelayed(this, 1000);
    }
}, 1000);

以及您的onBindViewHolder方法

public void onBindViewHolder(final FeedViewHolder holder, final int position) {

      updateTimeRemaining(endTime, holder.yourTextView);
}

private void updateTimeRemaining(long endTime, TextView yourTextView) {

    long timeDiff = endTime - System.currentTimeMillis();
    if (timeDiff > 0) {
        int seconds = (int) (timeDiff / 1000) % 60;
        int minutes = (int) ((timeDiff / (1000 * 60)) % 60);
        int hours = (int) ((timeDiff / (1000 * 60 * 60)) % 24);

        yourTextView.setText(MessageFormat.format("{0}:{1}:{2}", hours, minutes, seconds));
    } else {
        yourTextView.setText("Expired!!");
    }
}

如果您认为notifyDataSetChanged()每毫秒是错误的，那么这里是第二种选择。使用Runnable实现创建类，并使用setTag()和getTag()方法在适配器中使用

    public class DownTimer implements Runnable {

    private TextView yourTextView;
    private long endTime;
    private DateFormat formatter = new SimpleDateFormat("HH:mm:ss", Locale.getDefault());
    private Handler handler = new Handler();

    public DownTimer(long endTime, TextView textView) {
        this.endTime = endTime;
        yourTextView = textView;
        formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
    }

    public void setEndTime(long endTime) {
        this.endTime = endTime;
    }

    public void start() {
        if (handler != null)
            handler.postDelayed(this, 0);
    }

    public void cancel() {
        if (handler != null)
            handler.removeCallbacks(this);
    }

    @Override
    public void run() {
        if (handler == null)
            return;

        if (yourTextView == null && endTime == 0)
            return;

        long timeDiff = endTime - System.currentTimeMillis();

        try {
            Date date = new Date(timeDiff);
            yourTextView.setText(formatter.format(date));

        }catch (Exception e){e.printStackTrace();}
        }
}

像这样在onBindViewHolder中使用

if (holder.yourTextView.getTag() != null) {
    DownTimer downTimer = (DownTimer) holder.yourTextView.getTag();
    downTimer.cancel();
    downTimer.setEndTime(endTime);
    downTimer.start();
} else {
    DownTimer downTimer = new DownTimer(endTime, holder.yourTextView);
    downTimer.start();
    holder.yourTextView.setTag(downTimer);
}

滚动时，RecyclerView中的多个倒计时器会闪烁

3 个答案: