变量的Java final关键字 [英] Java final keyword for variables
本文介绍了变量的Java final关键字的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
final
关键字如何使变量不可变? 维基百科说没有。
How does the final
keyword not make a variable immutable? Wikipedia says it doesn't.
推荐答案
在Java中,术语 final 是指引用,而不可变是指对象。将 final
修饰符分配给引用意味着它不能更改为指向另一个对象,但如果对象本身是可变的,则可以对其进行修改。
In Java, the term final refers to references while immutable refers to objects. Assigning the final
modifier to a reference means it cannot change to point to another object, but the object itself can be modified if it is mutable.
例如:
final ArrayList<String> arr = new ArrayList<String>();
arr.add("hello"); // OK, the object to which arr points is mutated
arr = null; // Not OK, the reference is final and cannot be reassigned to
正如维基百科的文章所提到的,如果你来自C ++,你必须将 const
的概念分解为 final
和不可变。
As the Wikipedia article mentions, if you are coming from C++, you must dissociate the concept of const
into final
and immutable.
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