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Comments on Java generics, how to work around type erasure?

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Java generics, how to work around type erasure?

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This code doesn't compile:

package tryNcry;

public class ExampleClass<S extends SomeClass> {

	S[] createArray(int n) {
		return new S[n]; // obvious compile time ERROR here: 
                                 // Cannot create a generic array of S
	}
}

The reason for this is obvious: due to type erasure, at runtime there is no way for the JRE to know what S would have been, and so no way to create an array for type S.

Everything would be fine (if tedious) if there was any instance of S, using reflection.

How can I solve this?

java generics

posted 11 months ago

CC BY-SA 4.0

11mo ago by hkotsubo‭

watchmaker‭

76 reputation 7 0 15 5

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1 comment thread

Generics and arrays don’t mix well, for precisely the reasons you’ve encountered. The best solution ... (1 comment)

VGR‭ wrote 6 months ago

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Generics and arrays don’t mix well, for precisely the reasons you’ve encountered. The best solution by far is to avoid arrays and use a List instead:

List<S> createList(int n) {
        List<S> list = new ArrayList<>(n);
        list.addAll(Collections.nCopies(n, null));
        return list;
}

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Comments on Java generics, how to work around type erasure?

Java generics, how to work around type erasure?

1 comment thread