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What does a tilde in angle brackets mean when creating a Java generic class?

开发者 https://www.devze.com 2023-02-08 14:18 出处:网络
I was reading through some JMockit examples and found this code: final List<OrderItem> actualItems = new ArrayLis开发者_开发知识库t<~>();

I was reading through some JMockit examples and found this code:

final List<OrderItem> actualItems = new ArrayLis开发者_开发知识库t<~>();

What does the tilde in the generic identifier mean? I know it's the unary bitwise NOT operator, but I don't see an operand here.

Also, I tried compiling it and got an error. Am I just missing something?


It is just a shorthand for "same as in declaration".

Some IDEs, e.g. IntelliJ use this too.

The files on disk do not have this notation, which is only a compaction in the IDE GUI.


If there wasn't a tilde, I'd say, the code was already Java 7. Java 7 allows the diamond operator so this is/will be legal Java code:

Map<String, List<String>> map = new HashMap<>();

(but - no tilde with this syntax)


In IntelliJ IDEA, the ~ here:

Set<String> associations = new LinkedHashSet<~>();

means String, which is the same as in the declaration on the left side.


I think that is shorthand to mean whatever the type is, in this case OrderItem.

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