Android利用RecyclerView实现列表倒计时效果

时间:2022-07-27
本文章向大家介绍Android利用RecyclerView实现列表倒计时效果,主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项,具有一定的参考价值,需要的朋友可以参考一下。

最近面试时,面试官问了一个列表倒计时效果如何实现,现在记录一下。

运行效果图

实现思路

实现方法主要有两个: 1.为每个开始倒计时的item启动一个定时器,再做更新item处理; 2.只启动一个定时器,然后遍历数据,再做再做更新item处理。 经过思考,包括性能、实现等方面,决定使用第2种方式实现。

实现过程

数据实体

/** 
 * 总共的倒计时的时间(结束时间-开始时间),单位:毫秒 
 * 例: 2019-02-23 11:00:30 与 2019-02-23 11:00:00 之间的相差的毫秒数 
 */ 
 private long totalTime; 
 /** 
 * 倒计时是否在暂停状态 
 */ 
 private boolean isPause = true; 

倒计时

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()) {//不处于暂停状态
     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);
    }
   }
  }
 }

线程交互更新item

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

性能优化方面

1.调用notifyItemChanged()方法后,不要更新整个item(比如说item包含图片,不需要变的),所以要重写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;
  }
  //更新某个控件,比如说只需要更新时间信息,其他不用动
  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("剩余时间: " + day + "天" + hour + "小时" + min + "分" + s + "秒");
  holder.btnAction.setText(bean.isPause() ? "开始" : "暂停");
  holder.btnAction.setEnabled(bean.getTotalTime() != 0);
 }

2.销毁资源操作:

/**
  * 销毁资源
  */
 public void destroy() {
  mHandler.removeMessages(1);
  if (mTimer != null) {
   mTimer.cancel();
   mTimer.purge();
   mTimer = null;
  }
 }

RecyclerView.Adapter部分源码

public class CountDownTimerAdapter extends RecyclerView.Adapter<CountDownTimerAdapter.Holder  {
private static final String TAG = "CountDownTimerAdapter- ";
private List<CountDownTimerBean  mList;//数据
private Handler mHandler;//线程调度,用来更新列表
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);
}
/**
* 设置新的数据源
*
* @param list 数据
*/
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);
}
/**
* 销毁资源
*/
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;
}
//更新某个控件,比如说只需要更新时间信息,其他不用动
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("剩余时间: " + day + "天" + hour + "小时" + min + "分" + s + "秒");
holder.btnAction.setText(bean.isPause() ? "开始" : "暂停");
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("剩余时间: " + day + "天" + hour + "小时" + min + "分" + s + "秒");
holder.btnAction.setText(bean.isPause() ? "开始" : "暂停");
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("暂停");
} else {
bean.setPause(true);
holder.btnAction.setText("开始");
}
}
});
}
@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()) {//不处于暂停状态
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);
}
}
}
}
}

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