为什么最终对象可以修改？ [英] Why can final object be modified?

问题描述

我在我正在处理的代码库中遇到以下代码：

I came across the following code in a code base I am working on:

public final class ConfigurationService {
    private static final ConfigurationService INSTANCE = new ConfigurationService();
    private List providers;

    private ConfigurationService() {
        providers = new ArrayList();
    }

    public static void addProvider(ConfigurationProvider provider) {
        INSTANCE.providers.add(provider);
    }

    ...

INSTANCE宣布为最终。为什么可以将对象添加到INSTANCE？不应该使final的使用无效。 （它没有）。

INSTANCE is declared as final. Why can objects be added to INSTANCE? Shouldn't that invalidate the use of final. (It doesn't).

我假设答案必须用指针和内存做一些事情，但想知道肯定。

I'm assuming the answer has to do something with pointers and memory but would like to know for sure.

推荐答案

'final'只是使对象引用不可更改。它指向的对象不是通过这样做而不可变的。 INSTANCE永远不会引用另一个对象，但它引用的对象可能会改变状态。

'final' simply makes the object reference unchangeable. The object it points to is not immutable by doing this. INSTANCE can never refer to another object, but the object it refers to may change state.

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