How to Create a Time-Based Expiring Map in Java?

Java Time-Based Map/Cache with Expiring Keys

Q: Is there a built-in Java Map or similar data structure that automatically removes entries after a specified interval?

A: Yes, Google Collections (now known as Guava) provides a MapMaker class with the desired functionality:

ConcurrentMap<Key, Graph> graphs = new MapMaker()
   .concurrencyLevel(4)
   .softKeys()
   .weakValues()
   .maximumSize(10000)
   .expiration(10, TimeUnit.MINUTES)
   .makeComputingMap(
       new Function<Key, Graph>() {
         public Graph apply(Key key) {
           return createExpensiveGraph(key);
         }
       });

Note: As of Guava 10.0, the MapMaker methods mentioned above are deprecated in favor of the CacheBuilder class:

LoadingCache<Key, Graph> graphs = CacheBuilder.newBuilder()
    .maximumSize(10000)
    .expireAfterWrite(10, TimeUnit.MINUTES)
    .build(
        new CacheLoader<Key, Graph>() {
          public Graph load(Key key) throws AnyException {
            return createExpensiveGraph(key);
          }
        });

This CacheBuilder provides additional flexibility and a more modern API for managing cache behavior.

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