Built-In way to store Pre-Sorted Key-Value Pairs in Java?

I'm looking for a way to maintain the sorting on 开发者_运维技巧my key-value pairs. They are sorted by variables outside of the actual key-value pairs (for better UI). I am currently using a Hashtable, but that does not maintain the sorting =(

Hashtable<Integer, String> subscriptions = getUsersSubscriptions(user);

Is there some simple way that Java lets one store pairs? The best idea I can think of is using 2 associated ArrayLists (one of type Integer, another of type String). Can someone think of something better?

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If your key-value pairs are already sorted, LinkedHashMap will maintain order of insertion.

In other words, the keys returned by map.keySet() will be in the exact order you put them into the map.

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SortedMap<Integer, String> myMap = new TreeMap<Integer,String>();

If you have a custom sorting, pass a Comparator instance to the constructor of the TreeMap. But be careful doing so, as using a Comparator that does not go well with natural Integer order would make things impossible to understand and debug.

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LinkedHashMap can be used here.

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Is there some simple way that Java lets one store pairs?

Create a custom class that stores the two properties.

They are sorted by variables outside of the actual key-value pairs

Add a third property for the sort data.

Then your class can implement Comparable to sort the data as required based on this property.

Or you can use a custom Comparator to sort on the sort data field.

Now the class instances can be stored in an ArrayList.