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What does the <TYPE> in java mean?
Hello I came across this class while debugging , can someone give me pointers to what it means, please. Thanks.
class Something<P>{
private P someVariable;
}
//what does <P> mean here?
Thanks.
5 Answers
This is a generic. It allows you to write code that works with different types.
Try this tutorial:
It means its a generic class. You create a generic type declaration by changing the code
"public class Box" to "public class Box<T>"
For further information you can see this reference:
This is an example of class templating (although it is erased at runtime). Usually it is class and not class
. It allows you to inject a type into a class at compile time.
For example if you did
new Something<String>();
then the someVariable would be of type String.
If you called
new Something();
then I believe someVariable would be of type Object as it would have no inferred type information. Usually your IDE will give you a warning about this.
It is also described here.
P is a type used for generics.
Usually it is T, or TEntity, for type or entity type.
Just think of ArrayList<string> as an example where the type is string.
This is a Generic class definition. <P> is the place holder for an Object that get substituted at compile.
