对于将所有可能的变量都声明为final，我非常武断。这包括方法参数、局部变量，以及很少的值对象字段。我有三个在任何地方声明最终变量的主要原因:

Declaring Intention: By declaring a final variable, I am stating that this variable is meant to be written to only once. It's a subtle hint to other developers, and a big hint to the compiler. Enforcing Single-use Variables: I believe in the idea that each variable should have only one purpose in life. By giving each variable only one purpose, you reduce the time it takes to grok the purpose of that particular variable while debugging. Allows for Optimization: I know that the compiler used to have performance enhancement tricks which relied specifically on the immutability of a variable reference. I like to think some of these old performance tricks (or new ones) will be used by the compiler.

然而，我确实认为final类和方法远不如final变量引用有用。最后一个关键字，当与这些声明一起使用时，只是为自动化测试和以您从未预料到的方式使用代码提供了障碍。

强烈鼓励使用final作为常量。但是，我不会将它用于方法或类(或者至少考虑一下)，因为它使测试更加困难，如果不是不可能的话。如果一定要让一个类或方法成为final，请确保这个类实现了一些接口，这样就可以让一个模拟实现相同的接口。

我将它用于方法内部和外部的常量。

我有时只将它用于方法，因为我不知道子类是否不想覆盖给定的方法(无论出于什么原因)。

至于类，我只对一些基础类使用了final类。

IntelliJ IDEA会在函数参数被写入函数内部时发出警告。我已经停止使用final作为函数参数了。我在java运行库中也没有看到它们。

I have to read a lot of code for my job. Missing final on instance variables is one of the top things to annoy me and makes understanding the code unnecessarily difficult. For my money, final on local variables causes more clutter than clarity. The language should have been designed to make that the default, but we have to live with the mistake. Sometimes it is useful particularly with loops and definite assignment with an if-else tree, but mostly it tends to indicate your method is too complicated.

Final显然应该用在常量上，并加强不可变性，但在方法上还有另一个重要的用途。

Effective Java在这方面有一个完整的项目(项目15)，指出了意外继承的陷阱。实际上，如果您没有为继承而设计和记录您的类，那么从它继承可能会带来意想不到的问题(该项目提供了一个很好的例子)。因此，建议在不打算继承的任何类和/或方法上使用final。

That may seem draconian, but it makes sense. If you are writing a class library for use by others then you don't want them inheriting from things that weren't designed for it - you will be locking yourself into a particular implementation of the class for back compatibility. If you are coding in a team there is nothing to stop another member of the team from removing the final if they really have to. But the keyword makes them think about what they are doing, and warns them that the class they are inheriting from wasn't designed for it, so they should be extra careful.

当在Java中与变量一起使用时，Final提供了c++中常量的替代品。所以当final和static被用于一个变量时，它就变成了不可变的。同时让迁移的c++程序员非常开心;-)

当与引用变量一起使用时，它不允许您重新引用对象，尽管对象可以被操作。

当final与方法一起使用时，它不允许子类重写该方法。

一旦用法非常清楚，就应该谨慎使用。这主要取决于设计，因为在方法上使用final不利于多态性。

只有当你非常确定变量的值不会/不应该被改变时，才应该将它用于变量。还要确保您遵循SUN鼓励的编码约定。int COLOR_RED = 1;(大写字母以下划线分隔)

对于引用变量，只在需要对特定对象的不可变引用时使用它。

关于可读性部分，在使用最终修饰语时，注释起着非常重要的作用。