我正在尝试按日期对我的 arrayList
进行排序。每次收到通知并从那里检索时,我都会将日期存储在 Firebase 上。我正在使用 Collections.sort
但我不知道如何在我的代码中实现,因为我的日期格式以字符串格式的数字开头,例如“2017 年 7 月 12 日凌晨 12:00”。
我在 stackoverflow 上看过一些这样的例子,但我不知道如何让它在我的案例中起作用。我将在下面发布屏幕截图和我的代码。
日期未排序。
NotificationFragment.java
public class NotificationFragment extends Fragment {
prepareNotification1();
sortDate();
return v;
}
private void prepareNotification1() {
FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
String userID = user.getUid();
mRef.child("customers").child(userID).child("Notification").addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
Notification menu = dataSnapshot.getValue(Notification.class);
notificationList.add(menu);
mAdapter.notifyDataSetChanged();
}
});
}
public void sortDate() {
Collections.sort(notificationList, new Comparator<Notification>() {
@Override
public int compare(Notification lhs, Notification rhs) {
return lhs.getDate().compareTo(rhs.getDate());
}
});
mAdapter = new NotificationAdapter(getContext(), notificationList);
mRecyclerView.setAdapter(mAdapter);
}
}
MyFirebaseMessagingService.java
public class MyFirebaseMessagingService extends FirebaseMessagingService {
@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
Calendar cal = Calendar.getInstance();
String currentDateTimeString = DateFormat.getDateInstance().format(new Date());
SimpleDateFormat df = new SimpleDateFormat("hh:mm a");
String currentTime = df.format(cal.getTime());
String notificationTime = currentDateTimeString + " at " + currentTime;
Notification newNotification = new Notification(remoteMessage.getData().get("body"), notificationTime);
mRef.child("customers").child(userID).child("Notification").push().setValue(newNotification);
}
Notification.java
public class Notification {
private String message;
private String date;
public Notification(){
}
public Notification(String message, String date){
this.message = message;
this.date = date;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
最佳答案
解析日期后进行排序
Collections.sort(notificationList, new Comparator<Notification>() {
DateFormat f = new SimpleDateFormat("dd/MM/yyyy '@'hh:mm a");
@Override
public int compare(Notification lhs, Notification rhs) {
try {
return f.parse(lhs.getDate()).compareTo(f.parse(rhs.getDate()));
} catch (ParseException e) {
throw new IllegalArgumentException(e);
}
}
})
如果您的日期是其他格式,请相应地编写DateFormat。
关于java - Android - 如何按日期对 arrayList 进行排序?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/45049402/