Arrowhead brackets

[dushmantha.e]

I don't understand the usage of arrowhead brackets in java..

ex- List<Book> b=new ArrayList<Book>();

here Book is a class name...i'm new to this...please help:).

[JosAH]

I don't understand the usage of arrowhead brackets in java..

ex- List<Book> b=new ArrayList<Book>();

here Book is a class name...i'm new to this...please help:).

That is an example of Java Generics. It helps the programmer in compile time type safety (C++ has a similar looking feature 'class templates' but both are entirely different mechanisms).

kind regards,

Jos

[Singing Boyo]

Well, aside from the typical less than (<) and greater than(>) operations, it is generics. A generic argument is used to create classes that provide functionality for any objects or for any objects derived from a specific type. They are similar to C++ class templates, but while C++ creates completely separate classes for each generic/template argument used, Java does not - which means that you cannot create arrays of the generic argument, or cast anything to the generic argument type.

A full tutorial is here - Java Generics

[pbrockway2]

List<Book> b=new ArrayList<Book>();

This is read "list of books b is a new array list of books".

Generics is the ability to have lists (/maps/sets etc) of something. You use a line like the one to posted to declare and create them. And the compiler will complain if you try and use a member of the list as anything but a reference to a Book instance.

[dushmantha.e]

Thanks JosAH, it was helpfull:)

[dushmantha.e]

Thank you so much everybody sorry i so your replies now.:)