使用getter进行'public static final'或'private static final'？ [英] 'public static final' or 'private static final' with getter?

问题描述

在Java中，它教导变量应保持私有以实现更好的封装，但静态常量呢？这个：

In Java, it's taught that variables should be kept private to enable better encapsulation, but what about static constants? This:

public static final int FOO = 5;

结果与此相当：

private static final int FOO = 5;
...
public static getFoo() { return FOO; }

但哪种做法更好？

推荐答案

有一个原因是不能在代码中直接使用常量。

There's one reason to not use a constant directly in your code.

假设FOO可能会在稍后更改（但仍保持不变），说 public static final int FOO = 10; 。只要没有人愚蠢直接硬编码这个值，不应该破坏任何东西吗？

Assume FOO may change later on (but still stay constant), say to public static final int FOO = 10;. Shouldn't break anything as long as nobody's stupid enough to hardcode the value directly right?

没有。 Java编译器会将诸如Foo之类的常量内联到调用代码中，即 someFunc（FooClass.FOO）; 变为 someFunc（5）; 。现在，如果您重新编译库而不是调用代码，则最终会出现令人惊讶的情况。如果你使用一个函数就可以避免这种情况 - JIT仍然可以很好地优化它，所以没有真正的性能。

No. The Java compiler will inline constants such as Foo above into the calling code, i.e. someFunc(FooClass.FOO); becomes someFunc(5);. Now if you recompile your library but not the calling code you can end up in surprising situations. That's avoided if you use a function - the JIT will still optimize it just fine, so no real performance hit there.

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