How to convert Map to Map ? (option : using guava)

Question

I have a Map the String key is nothing but numeric value like \"123\" etc. I\'m getting numeric value because this values are

Answer 1

UPDATE for Java 8

You can use streams to do this:

Map newMap = oldMap.entrySet().stream()
  .collect(Collectors.toMap(e -> Long.parseLong(e.getKey()), Map.Entry::getValue));

This assumes that all keys are valid string-representations of Longs. Also, you can have collisions when transforming; for example, "0" and "00" both map to 0L.

---

I would think that you'd have to iterate over the map:

Map newMap = new HashMap();
for(Map.Entry entry : map.entrySet()) {
   newMap.put(Long.parseLong(entry.getKey()), entry.getValue());
}

This code assumes that you've sanitized all the values in map (so no invalid long values).

I'm hoping there is a better solution.

EDIT

I came across the CollectionUtils#transformedCollection(Collection, Transformer) method in Commons Collection-Utils that looks like it might do what you want. Scratch that, it only works for classes that implement Collection.