How to get type of generic interface in java

Question

I have a class Bucket which is passed as a generic type in the Comparator interface. I am working with GSON to register a type adapter for this type.

The typeadapter function has the signature

public GsonBuilder registerTypeAdapter(Type type, Object typeAdapter)

I want to pass the first argument as the type object

java.util.Comparator<org.elasticsearch.search.aggregations.bucket.terms.Terms$Bucket>

I tried Comparator<Terms.Bucket>.class which throws me a syntax error . What is the correct way of doing this ?

You need to pass the `type` object as a parameter. Not a `.class ` — Pankaj Singhal, Oct 09 '18 at 10:36
See if this helps: https://stackoverflow.com/questions/9111899/how-do-i-build-a-java-type-object-at-runtime-from-a-generic-type-definition-and — Yoav Gur, Oct 09 '18 at 10:42

kAliert · Answer 1 · 2018-10-09T11:32:00.880

1

Generics are only used for compile time safety, then they are erased (they don't exist at runtime). So writing something like this Comparator<Terms.Bucket>.class isnt possible. You need to create a explicit class:

public class BucketComparator implements Comparator<Terms.Bucket>
{
    ...
}

After this you are able to pass the type as follows: BucketComparator.class

edited Oct 09 '18 at 11:32

answered Oct 09 '18 at 10:31

kAliert

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How to get type of generic interface in java

1 Answers1