RecyclerView中怎么實現列表倒計時

這篇文章將為大家詳細講解有關RecyclerView中怎么實現列表倒計時，文章內容質量較高，因此小編分享給大家做個參考，希望大家閱讀完這篇文章后對相關知識有一定的了解。

首先看下實現的最終效果

如何顯示列表我相信大家都會，這里我只附上和倒計時功能實現的adapter類。

public class ClockAdapter extends RecyclerView.Adapter<ClockAdapter.ClockViewHolder> { private SparseArray<CountDownTimer> countDownMap = new SparseArray<>(); @Override public ClockViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {  View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_rv, parent, false);  return new ClockViewHolder(view); } /**  * 清空資源  */ public void cancelAllTimers() {  if (countDownMap == null) {   return;  }  for (int i = 0,length = countDownMap.size(); i < length; i++) {   CountDownTimer cdt = countDownMap.get(countDownMap.keyAt(i));   if (cdt != null) {    cdt.cancel();   }  } } @Override public void onBindViewHolder(final ClockViewHolder holder, int position) {  long betweenDate;  if (position == 0) {   betweenDate= DateUtil.getLeftTime("2017-8-8 12:10:10");  } else {   betweenDate= DateUtil.getLeftTime("2017-8-9 15:10:10");  }  if (holder.countDownTimer != null) {   holder.countDownTimer.cancel();  }  if (betweenDate > 0) {   holder.countDownTimer = new CountDownTimer(betweenDate, 1000) {    public void onTick(long millisUntilFinished) {     millisUntilFinished = millisUntilFinished / 1000;     int hours = (int) (millisUntilFinished / (60 * 60));     int leftSeconds = (int) (millisUntilFinished % (60 * 60));     int minutes = leftSeconds / 60;     int seconds = leftSeconds % 60;     final StringBuffer sBuffer = new StringBuffer();     sBuffer.append(addZeroPrefix(hours));     sBuffer.append(":");     sBuffer.append(addZeroPrefix(minutes));     sBuffer.append(":");     sBuffer.append(addZeroPrefix(seconds));     holder.clock.setText(sBuffer.toString());    }    public void onFinish() {//     時間結束后進行相應邏輯處理    }   }.start();   countDownMap.put(holder.clock.hashCode(), holder.countDownTimer);  } else {//   時間結束 進行相應邏輯處理  } } @Override public int getItemCount() {  return 25; } class ClockViewHolder extends RecyclerView.ViewHolder {  TextView clock;  CountDownTimer countDownTimer;  public ClockViewHolder(View itemView) {   super(itemView);   clock = (TextView) itemView.findViewById(R.id.clock);  } }}

其中cancelAllTimer()這個方法解決了內存的問題，通過這行代碼，將item的hashcode作為key設入SparseArray中，這樣在cancelAllTimer方法中可以一個一個取出來進行倒計時取消操作。

countDownMap.put(holder.clock.hashCode(),holder.countDownTimer);

接著通過下面這行代碼新建一個CountDownTimer類

holder.countDownTimer = new CountDownTimer(betweenDate, 1000) { public void onTick(long millisUntilFinished) { millisUntilFinished = millisUntilFinished / 1000; int hours = (int) (millisUntilFinished / (60 * 60)); int leftSeconds = (int) (millisUntilFinished % (60 * 60)); int minutes = leftSeconds / 60; int seconds = leftSeconds % 60; final StringBuffer sBuffer = new StringBuffer(); sBuffer.append(addZeroPrefix(hours)); sBuffer.append(":")   sBuffer.append(addZeroPrefix(minutes));     sBuffer.append(":");     sBuffer.append(addZeroPrefix(seconds));     holder.clock.setText(sBuffer.toString());}public void onFinish() {// 時間結束后進行相應邏輯處理}}.start();

分析它的源碼

public CountDownTimer(long millisInFuture, long countDownInterval) {  mMillisInFuture = millisInFuture;  mCountdownInterval = countDownInterval; }

從中可以很清楚的看出，設置了兩個值，第一個是倒計時結束時間，第二個是刷新時間的間隔時間。 然后通過start方法進行啟動，接著看下start方法中進行的處理

public synchronized final CountDownTimer start() {  mCancelled = false;  if (mMillisInFuture <= 0) {   onFinish();   return this;  }  mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;  mHandler.sendMessage(mHandler.obtainMessage(MSG));  return this; }

源碼中，當倒計時截止時間小于等0時也就是倒計時結束時，調用了onFinish方法，若時間還未結束，則通過handler的異步消息機制，將消息進行發出，通過一整個流程，最終方法會走到handler的handleMessage方法中，如果有不熟悉這個異步流程的伙伴，可以去看我以前寫的一篇異步消息機制的文章 android異步消息機制，源碼層面徹底解析。好了，接下來就來看看handler的handleMessage方法。

private Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) {  synchronized (CountDownTimer.this) {  if (mCancelled) {   return;  }  final long millisLeft = mStopTimeInFuture - SystemClock.elapsedRealtime();  if (millisLeft <= 0) {   onFinish();  } else if (millisLeft < mCountdownInterval) {  // no tick, just delay until done  sendMessageDelayed(obtainMessage(MSG), millisLeft);  } else {long lastTickStart=SystemClock.elapsedRealtime();   onTick(millisLeft); // take into account user's onTick taking time to execute long delay = lastTickStart + mCountdownInterval - SystemClock.elapsedRealtime();// special case: user's onTick took more than interval to// complete, skip to next interval while (delay < 0) delay += mCountdownInterval;  sendMessageDelayed(obtainMessage(MSG), delay);    }   }  } };

關于RecyclerView中怎么實現列表倒計時就分享到這里了，希望以上內容可以對大家有一定的幫助，可以學到更多知識。如果覺得文章不錯，可以把它分享出去讓更多的人看到。