CODEWITHSUNDEEP
javadictionary
user1081596
user1081596

Reputation: 907

Can I have a key-key map (as opposed to key-value) in Java?

What if I need to quickly search not only by the key but also by value. In other words, is there a construction like key-key as opposed to key-value?

Upvotes: 8

Views: 200

Answers (3)

j.snyder
j.snyder

Reputation: 535

To clarify, you would have some sort of map with the following key:value pairs:

Map<String, String> map = new HashMap<String, String>();
map.put("foo", "Freddy");
map.put("bar", "Bobby");

Then, you would want to do map.get("foo") and get Freddy, or do map.get("Freddy") and get foo?

If so, check this post out.

Upvotes: 0

Jesper
Jesper

Reputation: 206766

Several libraries have something like that. For example, Google Guava has a BiMap (bidirectional map). Unfortunately there's no bidirectional map in the standard Java library.

Upvotes: 5

Jon Skeet
Jon Skeet

Reputation: 1499760

Sounds like you want a bimap - I'd use the implementations in Guava if I were you; there's a BiMap interface, and various implementations such as HashBiMap and ImmutableBiMap.

Note that you generally view a BiMap from one "side" (K1 to K2), and just call inverse() to get the opposite view of things (K2 to K1).

Upvotes: 9

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