Android利用RecyclerView實(shí)現(xiàn)列表倒計(jì)時(shí)效果

來(lái)源：本站原創(chuàng)|時(shí)間：2020-01-10|欄目：Android|點(diǎn)擊：次

最近面試時(shí)，面試官問(wèn)了一個(gè)列表倒計(jì)時(shí)效果如何實(shí)現(xiàn)，現(xiàn)在記錄一下。

運(yùn)行效果圖

實(shí)現(xiàn)思路

實(shí)現(xiàn)方法主要有兩個(gè)：
1.為每個(gè)開始倒計(jì)時(shí)的item啟動(dòng)一個(gè)定時(shí)器，再做更新item處理；
2.只啟動(dòng)一個(gè)定時(shí)器，然后遍歷數(shù)據(jù)，再做再做更新item處理。
經(jīng)過(guò)思考，包括性能、實(shí)現(xiàn)等方面，決定使用第2種方式實(shí)現(xiàn)。

實(shí)現(xiàn)過(guò)程

數(shù)據(jù)實(shí)體

/** 
 * 總共的倒計(jì)時(shí)的時(shí)間(結(jié)束時(shí)間-開始時(shí)間),單位：毫秒 
 * 例: 2019-02-23 11:00:30 與 2019-02-23 11:00:00 之間的相差的毫秒數(shù) 
 */ 
 private long totalTime; 
 /** 
 * 倒計(jì)時(shí)是否在暫停狀態(tài) 
 */ 
 private boolean isPause = true;

倒計(jì)時(shí)

Timer

mTimer.schedule(mTask, 0, 1000);

TimerTask

 class MyTask extends TimerTask {
  @Override
  public void run() {
   if (mList.isEmpty()) {
    return;
   }
   int size = mList.size();
   CountDownTimerBean bean;
   long totalTime;
   for (int i = 0; i < size; i++) {
    bean = mList.get(i);
    if (!bean.isPause()) {//不處于暫停狀態(tài)
     totalTime = bean.getTotalTime() - 1000;
     if (totalTime <= 0) {
      bean.setPause(true);
      bean.setTotalTime(0);
     }
     bean.setTotalTime(totalTime);
     Message message = mHandler.obtainMessage(1);
     message.arg1 = i;
     mHandler.sendMessage(message);
    }
   }
  }
 }

線程交互更新item

mHandler = new Handler(Looper.getMainLooper()) {
   @Override
   public void handleMessage(Message msg) {
    switch (msg.what) {
     case 1:
      notifyItemChanged(msg.arg1, "update-time");
      break;
    }
   }
  };

性能優(yōu)化方面

1.調(diào)用notifyItemChanged()方法后，不要更新整個(gè)item(比如說(shuō)item包含圖片，不需要變的)，所以要重寫onBindViewHolder( Holder , int , List )方法：

@Override
 public void onBindViewHolder(@NonNull Holder holder, int position, @NonNull List<Object> payloads) {
  if (payloads.isEmpty()) {
   onBindViewHolder(holder, position);
   return;
  }
  //更新某個(gè)控件,比如說(shuō)只需要更新時(shí)間信息，其他不用動(dòng)
  CountDownTimerBean bean = mList.get(position);
  long day = bean.getTotalTime() / (1000 * 60 * 60 * 24);
  long hour = (bean.getTotalTime() / (1000 * 60 * 60) - day * 24);
  long min = ((bean.getTotalTime() / (60 * 1000)) - day * 24 * 60 - hour * 60);
  long s = (bean.getTotalTime() / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
  holder.tvTime.setText("剩余時(shí)間: " + day + "天" + hour + "小時(shí)" + min + "分" + s + "秒");
  holder.btnAction.setText(bean.isPause() ? "開始" : "暫停");
  holder.btnAction.setEnabled(bean.getTotalTime() != 0);
 }

2.銷毀資源操作：

/**
  * 銷毀資源
  */
 public void destroy() {
  mHandler.removeMessages(1);
  if (mTimer != null) {
   mTimer.cancel();
   mTimer.purge();
   mTimer = null;
  }
 }

RecyclerView.Adapter部分源碼

public class CountDownTimerAdapter extends RecyclerView.Adapter<CountDownTimerAdapter.Holder> {
 private static final String TAG = "CountDownTimerAdapter->";
 private List<CountDownTimerBean> mList;//數(shù)據(jù)
 private Handler mHandler;//線程調(diào)度，用來(lái)更新列表

 private Timer mTimer;
 private MyTask mTask;

 public CountDownTimerAdapter() {
  mList = new ArrayList<>();
  mHandler = new Handler(Looper.getMainLooper()) {
   @Override
   public void handleMessage(Message msg) {
    switch (msg.what) {
     case 1:
      notifyItemChanged(msg.arg1, "update-time");
      break;
    }
   }
  };
  mTask = new MyTask();
 }

 public void bindAdapterToRecyclerView(@NonNull RecyclerView view) {
  view.setAdapter(this);
 }

 /**
  * 設(shè)置新的數(shù)據(jù)源
  *
  * @param list 數(shù)據(jù)
  */
 public void setNewData(@NonNull List<CountDownTimerBean> list) {
  destroy();
  mList.clear();
  mList.addAll(list);
  notifyDataSetChanged();
  if (mTimer == null) {
   mTimer = new Timer();
  }
  mTimer.schedule(mTask, 0, 1000);
 }

 /**
  * 銷毀資源
  */
 public void destroy() {
  mHandler.removeMessages(1);
  if (mTimer != null) {
   mTimer.cancel();
   mTimer.purge();
   mTimer = null;
  }
 }

 @NonNull
 @Override
 public Holder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
  View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item_count_down_timer, viewGroup, false);
  return new Holder(view);
 }

 @Override
 public void onBindViewHolder(@NonNull Holder holder, int position, @NonNull List<Object> payloads) {
  if (payloads.isEmpty()) {
   onBindViewHolder(holder, position);
   return;
  }
  //更新某個(gè)控件,比如說(shuō)只需要更新時(shí)間信息，其他不用動(dòng)
  CountDownTimerBean bean = mList.get(position);
  long day = bean.getTotalTime() / (1000 * 60 * 60 * 24);
  long hour = (bean.getTotalTime() / (1000 * 60 * 60) - day * 24);
  long min = ((bean.getTotalTime() / (60 * 1000)) - day * 24 * 60 - hour * 60);
  long s = (bean.getTotalTime() / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
  holder.tvTime.setText("剩余時(shí)間: " + day + "天" + hour + "小時(shí)" + min + "分" + s + "秒");
  holder.btnAction.setText(bean.isPause() ? "開始" : "暫停");
  holder.btnAction.setEnabled(bean.getTotalTime() != 0);
 }

 @Override
 public void onBindViewHolder(@NonNull final Holder holder, int position) {
  holder.ivIcon.setImageResource(R.mipmap.ic_launcher_round);
  final CountDownTimerBean bean = mList.get(position);
  long day = bean.getTotalTime() / (1000 * 60 * 60 * 24);
  long hour = (bean.getTotalTime() / (1000 * 60 * 60) - day * 24);
  long min = ((bean.getTotalTime() / (60 * 1000)) - day * 24 * 60 - hour * 60);
  long s = (bean.getTotalTime() / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
  holder.tvTime.setText("剩余時(shí)間: " + day + "天" + hour + "小時(shí)" + min + "分" + s + "秒");
  holder.btnAction.setText(bean.isPause() ? "開始" : "暫停");
  holder.btnAction.setEnabled(bean.getTotalTime() != 0);
  holder.btnAction.setOnClickListener(new View.OnClickListener() {
   @Override
   public void onClick(View v) {
    if (bean.isPause()) {
     bean.setPause(false);
     holder.btnAction.setText("暫停");
    } else {
     bean.setPause(true);
     holder.btnAction.setText("開始");
    }
   }
  });
 }

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

 class Holder extends RecyclerView.ViewHolder {
  private ImageView ivIcon;
  private TextView tvTime;
  private Button btnAction;

  Holder(@NonNull View itemView) {
   super(itemView);
   ivIcon = itemView.findViewById(R.id.iv_icon);
   tvTime = itemView.findViewById(R.id.tv_time);
   btnAction = itemView.findViewById(R.id.btn_action);
  }
 }

 class MyTask extends TimerTask {
  @Override
  public void run() {
   if (mList.isEmpty()) {
    return;
   }
   int size = mList.size();
   CountDownTimerBean bean;
   long totalTime;
   for (int i = 0; i < size; i++) {
    bean = mList.get(i);
    if (!bean.isPause()) {//不處于暫停狀態(tài)
     totalTime = bean.getTotalTime() - 1000;
     if (totalTime <= 0) {
      bean.setPause(true);
      bean.setTotalTime(0);
     }
     bean.setTotalTime(totalTime);
     Message message = mHandler.obtainMessage(1);
     message.arg1 = i;
     mHandler.sendMessage(message);
    }
   }
  }
 }
}

項(xiàng)目地址：Android利用RecyclerView實(shí)現(xiàn)列表倒計(jì)時(shí)效果

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Android利用RecyclerView實(shí)現(xiàn)列表倒計(jì)時(shí)效果

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