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Java Forum / General / March 2008"value" to find a "key"
Is there such a "Map" in java I can easily trace the key by its value, assuming the values are also unique ? John, > Is there such a "Map" in java I can easily trace the key by its value, > assuming the values are also unique ? Not that I know of. You could always use two Maps, one for name-to-phone and the other for phone-to-name. If you happen to know *for certain* that names and numbers are never alike, you could use a single Map and enter each item twice, once as name-and-phone and once as phone-and-name.  SignatureEric.Sosman@sun.com Thanks Eric, I think I will try your second suggestion. John, > > Is there such a "Map" in java I can easily trace the key by its value, > > assuming the values are also unique ? [quoted text clipped - 7 lines] > -- > Eric.Sos...@sun.com >Is there such a "Map" in java I can easily trace the key by its value, >assuming the values are also unique ? You create a second map where your values act as keys. -- Roedy Green Canadian Mind Products The Java Glossary http://mindprod.com > Is there such a "Map" in java I can easily trace the key by its value, > assuming the values are also unique ? http://commons.apache.org/collections/apidocs/org/apache/commons/collections/bid imap/TreeBidiMap.html > Is there such a "Map" in java I can easily trace the key by its value, > assuming the values are also unique ? > > John, The map you imaged does not exist in the JDK.. But if the values are unique, you can use two maps to resolve that problem. A--B and B--A >> Is there such a "Map" in java I can easily trace the key by its value, >> assuming the values are also unique ? [quoted text clipped - 5 lines] > problem. > A--B and B--A You can also have each Map's value be some kind of Pair class that holds the A and B values in a single object. That way you have both items whichever Map you used to reach it, and their association is preserved while you're using them. The different Maps analogize to multiple indexes in a database, all organizing the same tuples via different lookup keys. SignatureLew Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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