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Is it fine to write following?

Set<Integer> integs = new HashSet<>();

Inside <>, is it fine to leave it as empty?

hatellla
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    Yes, diamond operator `<>` will infer `` as generic type from reference type. Now where is that duplicate... – Pshemo Apr 17 '15 at 10:23
  • Also see http://stackoverflow.com/questions/4166966/what-is-the-point-of-the-diamond-operator-in-java-7 – Radiodef Apr 17 '15 at 10:26
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    This has already been answered here : http://stackoverflow.com/questions/8660202/what-does-mean-for-java-generics – SR_ Apr 17 '15 at 10:26

4 Answers4

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As from Java 7, the compiler will infer the data type of the hash set without the need to write it twice.

Note though that there are some scenarios where the compiler might fail to infer the type, so you could get compilation errors for more complex scenarios.

More of that here.

npinti
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Yes this is a feature introduced in Java 7 where the <> is called the diamond operator. See http://docs.oracle.com/javase/7/docs/technotes/guides/language/type-inference-generic-instance-creation.html.

M A
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Yes if you're using java 7 or higher as described in documentation

You can replace the type arguments required to invoke the constructor of a generic class with an empty set of type parameters (<>) as long as the compiler can infer the type arguments from the context. This pair of angle brackets is informally called the diamond.

Jordi Castilla
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Yes. In your case, It'll take it as integer in Java 7 and later versions. Please find the confirmation from the Java documentation. http://docs.oracle.com/javase/7/docs/technotes/guides/language/type-inference-generic-instance-creation.html

Rajesh
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