Little doubts about java generic classes
習慣沉默
習慣沉默 2017-05-17 10:03:19
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There is a class defined as class Gift<T>{...},
When I create a new Gift object, such as Gift<Phone> ; myGift = new Gift<Phone>
What type is the myGift object? Is it Gift, Phone, or Object?
I read a paragraph on a blog that When instantiating an object, if you don’t specify a generic, the default is: Object, but if you don’t specify a generic, shouldn’t the default be GIft?

習慣沉默
習慣沉默

reply all(3)
PHPzhong

<T> This is just a generic declaration Gift<T> It means that you have the use of the generic type T in Gift. Java follows the principle of declaring first and then calling, so you need to declare the specific type of T before using T. The type of myGift has nothing to do with it. No matter what the type of T is, myGift is an object of a class called Gift.
Hope to adopt it!

滿天的星座

My personal understanding is that the restrictions of this type are restrictions on the parameters passed in, not the class itself

小葫芦

Gift, if you don’t specify a generic type, the default is: Object. That's for T, right? Java's generics need to determine the type during the compilation phase, and are not truly dynamic. So if the T type is not declared, T is assumed to be object by default

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