CODEWITHSUNDEEP
javaobjectdictionaryguava
me.at.coding
me.at.coding

Reputation: 17654

Transform Map to object using Guava?

Using Guava, is it possible to convert a Map to a Set or List of objects containing the keys and values of the Map? E.g. given something like

class MyEntry {
    public String key;
    public String value;
}

Map<String,String> theMap = new Map<String,String>();

I am missing something like this in Guava / did not find it:

Set<MyEntry> myEntries = Maps.transform(theMap, transformFunction<<Map<String,String>, MyEntry>);

Obviously it's not hard to do this manually, still I am wondering if I missed something and Guava really doesn't support such a thing?

Thanks for any hint!

Upvotes: 1

Views: 3001

Answers (1)

Louis Wasserman
Louis Wasserman

Reputation: 198123

The closest thing you can do with Guava would be something like

Collection<MyEntry> myEntries = Collections2.transform(map.entrySet(), function);

which is just a normal transformation on the entrySet of the map, and function has the type Function<Map.Entry<String, String>, MyEntry>.

Guava can't provide Sets.transform for a variety of reasons -- it can't guarantee the function is injective, it doesn't have an inverse to the function, etc. If you need a Set, then you're probably best off just doing the manual loop.

Upvotes: 4

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