Guava - Collections - Immutable collections

通篇看下来，主要讲Immutable Collections在防御性编程上的应用

 

首先要先了解下 defensive copy 

http://blog.csdn.net/tounaobun/article/details/8607174

 

官方wiki的介绍也基本是讲 Immutable Collections主要用在防御性编程上会使程序更安全，并且对比了jdk的Collections.unmodifiableXXX methods

 

优势：

Immutable objects have many advantages, including:

• Safe for use by untrusted libraries.
• Thread-safe: can be used by many threads with no risk of race conditions.
• Doesn't need to support mutation, and can make time and space savings with that assumption. All immutable collection implementations are more memory-efficient than their mutable siblings (analysis)
• Can be used as a constant, with the expectation that it will remain fixed

对比JDK的

The JDK provides Collections.unmodifiableXXX methods, but in our opinion, these can be

• unwieldy and verbose; unpleasant to use everywhere you want to make defensive copies
• unsafe: the returned collections are only truly immutable if nobody holds a reference to the original collection
• inefficient: the data structures still have all the overhead of mutable collections, including concurrent modification checks, extra space in hash tables, etc.

 

然后介绍了几种创建Immutable Collection 的方法（详情可参见官网）

 

 

 

 

总结，可能更适合“高级程序员”吧，目前就当看看，储备知识，而且很多时候复制后就是希望修改的（并不是设计为防御性的）

 

实用性：中