问题描述
我有一个列表视图（含自定义列表适配器），我需要显示在每一行倒计时。
I have a listview (with a custom list adapter), I need to display a countdown on every row.
例如，如果我的列表中包含4项，我将有4行。
在这一点上，我需要处理4个不同的倒计时（每个行），因为时间是不同的。
For example, if my list contains 4 items, I will have 4 rows.At this point, I need to handle 4 different countdowns (one for each row) because time is different.
到目前为止，我处理它的方式如下：在自定义列表适配器，里面getView（）方法创建TextView的里面一个新的CountDownTimer并显示剩余时间。
So far, I'm handling it the following way : in the Custom List Adapter, inside getView() method I create a new CountDownTimer and display remaining time inside TextView.
但问题是，它减慢活动很多，我甚至不能正确地在最坏的情况下滚动（因为显示一排每一次，它会创建一个新的CountDownTimer）。
But the problem is that it slows the activity a lot, I can't even scroll correctly in the worst cases (because each time a row is displayed, it creates a new CountDownTimer).
我搜索了很多了更好的解决方案，但没有一个是令人满意的。
I searched a lot for a better solution, but no one was satisfying.
有一个更清洁，更平滑的解决方案来处理一个ListView内的多个倒计时？
Is there a cleaner and smoother solution to handle multiple countdown timers inside a listView ?
感谢
推荐答案
而不是试图显示所有的剩余时间，这个想法是，以更新其可见的物品的剩余时间。
Instead of trying to show the remaining time for all, the idea is to update the remaining time for the items which are visible.
请按照下面的示例code，让我知道：
Please follow the following sample code and let me know :
MainActivity：
MainActivity :
public class MainActivity extends Activity {
private ListView lvItems;
private List<Product> lstProducts;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lvItems = (ListView) findViewById(R.id.lvItems);
lstProducts = new ArrayList<>();
lstProducts.add(new Product("A", System.currentTimeMillis() + 10000));
lstProducts.add(new Product("B", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("C", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("D", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("E", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("F", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("G", System.currentTimeMillis() + 30000));
lstProducts.add(new Product("H", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("I", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("J", System.currentTimeMillis() + 40000));
lstProducts.add(new Product("K", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("L", System.currentTimeMillis() + 50000));
lstProducts.add(new Product("M", System.currentTimeMillis() + 60000));
lstProducts.add(new Product("N", System.currentTimeMillis() + 20000));
lstProducts.add(new Product("O", System.currentTimeMillis() + 10000));
lvItems.setAdapter(new CountdownAdapter(MainActivity.this, lstProducts));
}
private class Product {
String name;
long expirationTime;
public Product(String name, long expirationTime) {
this.name = name;
this.expirationTime = expirationTime;
}
}
public class CountdownAdapter extends ArrayAdapter<Product> {
private LayoutInflater lf;
private List<ViewHolder> lstHolders;
private Handler mHandler = new Handler();
private Runnable updateRemainingTimeRunnable = new Runnable() {
@Override
public void run() {
synchronized (lstHolders) {
long currentTime = System.currentTimeMillis();
for (ViewHolder holder : lstHolders) {
holder.updateTimeRemaining(currentTime);
}
}
}
};
public CountdownAdapter(Context context, List<Product> objects) {
super(context, 0, objects);
lf = LayoutInflater.from(context);
lstHolders = new ArrayList<>();
startUpdateTimer();
}
private void startUpdateTimer() {
Timer tmr = new Timer();
tmr.schedule(new TimerTask() {
@Override
public void run() {
mHandler.post(updateRemainingTimeRunnable);
}
}, 1000, 1000);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
holder = new ViewHolder();
convertView = lf.inflate(R.layout.list_item, parent, false);
holder.tvProduct = (TextView) convertView.findViewById(R.id.tvProduct);
holder.tvTimeRemaining = (TextView) convertView.findViewById(R.id.tvTimeRemaining);
convertView.setTag(holder);
synchronized (lstHolders) {
lstHolders.add(holder);
}
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.setData(getItem(position));
return convertView;
}
}
private class ViewHolder {
TextView tvProduct;
TextView tvTimeRemaining;
Product mProduct;
public void setData(Product item) {
mProduct = item;
tvProduct.setText(item.name);
updateTimeRemaining(System.currentTimeMillis());
}
public void updateTimeRemaining(long currentTime) {
long timeDiff = mProduct.expirationTime - currentTime;
if (timeDiff > 0) {
int seconds = (int) (timeDiff / 1000) % 60;
int minutes = (int) ((timeDiff / (1000 * 60)) % 60);
int hours = (int) ((timeDiff / (1000 * 60 * 60)) % 24);
tvTimeRemaining.setText(hours + " hrs " + minutes + " mins " + seconds + " sec");
} else {
tvTimeRemaining.setText("Expired!!");
}
}
}
}
activity_main.xml中：
activity_main.xml :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="@+id/lvItems"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
list_item.xml
list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="5dp">
<TextView
android:id="@+id/tvProduct"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="Product Name"
android:textSize="16dp"
android:textStyle="bold" />
<TextView
android:id="@+id/tvTimeRemaining"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:text="Time Remaining : " />
</LinearLayout>
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