在Java中，当类型后跟尖括号（如List< Foo>）时，这意味着什么？ [英] In Java, what does it mean when a type is followed by angle brackets (as in List<Foo>)?

问题描述

我有时在另一个对象类型声明旁看到<>内的类型对象。
例如：

  NavigableMap< Double，Integer> colorMap = new TreeMap< Double，Integer>（）
或
 private final CopyOnWriteArrayList< EventListener> ListenerRecords = 
 CopyOnWriteArrayList< EventListener>（）; 
  

您能否给我一个简单的解释？

解决方案

java.sun.com/developer/technicalArticles/J2SE/generics/rel =nofollow noreferrer> http://java.sun.com/developer/technicalArticles/J2SE/generics/

I saw sometimes a type object inside <> beside of another object type declaration. For instance:

NavigableMap<Double, Integer> colorMap = new TreeMap<Double, Integer>()
or
private final CopyOnWriteArrayList<EventListener> ListenerRecords =
new CopyOnWriteArrayList<EventListener>(); 

Could you give me an easy explication?

解决方案

They're known as generics in java, and templates in C++.

http://java.sun.com/developer/technicalArticles/J2SE/generics/

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