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sorting arrayList of a class according to a field  RSS feed

 
David Freed
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Dear All,
we have an Arraylist<Tweet>, and this class is defined as followe:

now if we implement the method comparteTo, then will it be sorted automatically?
I want to sort this array by any insert.

Thank you in advance..
best,
David
 
Campbell Ritchie
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What array? You don't have an array. You have a List.

No, it will not iterate in order of sorting. It will iterate in insertion order. If you want iteration of that List in sorted order you must call a sort method:-
 
David Freed
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Thank you, yes i meant ArrayList.

but I want an efficient way, when we have lots of data, then sorting by any insert is not efficient.


Campbell Ritchie wrote:What array? You don't have an array. You have a List.

No, it will not iterate in order of sorting. It will iterate in insertion order. If you want iteration of that List in sorted order you must call a sort method:-
 
Maneesh Godbole
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Also check out Collections#sort(List<T> list,Comparator<? super T> c);
More detals here: http://www.vogella.com/tutorials/JavaCollections/article.html#collectionssort
 
David Freed
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Thank you, but I dont want to sort all of the list after each insert, it is not efficient in the big data set. this list will be just partially unsorted, it doesn't need to be sorted completely.

isn't there any other way?

Maneesh Godbole wrote:Also check out Collections#sort(List<T> list,Comparator<? super T> c);
More detals here: http://www.vogella.com/tutorials/JavaCollections/article.html#collectionssort
 
Dennis Grimbergen
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If you perform more writes than reads to your list, then you can choose to only sort on data retrieval from that list. And then don't sort after an addition to the list.
 
Darryl Burke
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If your List contains no duplicates, you can use a SortedSet.
 
Campbell Ritchie
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Go through the Collections class and see whether there is any way to sort part of the List. I don't think there is. You can create a sublist, sort that, and copy it back, however.

In Java8 you can probably use a Stream. Maybe something like this:-
myList.stream().sorted().toArray()
…which gives an array. Cast that array to Tweet[] and you can use it to create a List.

There must be a better way to create a List. I shall challenge you to find it. A good source about all things List‑y is the Java Tutorials, so start there.
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