问题
I was reading through some JMockit examples and found this code:
final List<OrderItem> actualItems = new ArrayList<~>();
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?
回答1:
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.
回答2:
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)
回答3:
In IntelliJ IDEA, the ~ here:
Set<String> associations = new LinkedHashSet<~>();
means String, which is the same as in the declaration on the left side.
回答4:
I think that is shorthand to mean whatever the type is, in this case OrderItem.
来源：https://stackoverflow.com/questions/4887876/what-does-a-tilde-in-angle-brackets-mean-when-creating-a-java-generic-class