什么时候不要在 Java 中使用 static 关键字? [英] When NOT to use the static keyword in Java?

问题描述

在 Java 中在方法签名上使用 static 关键字何时被认为是不好的做法?如果一个方法基于一些参数执行一个函数，并且不需要访问非静态字段，那么你不是总是希望这些类型的方法是静态的吗?

When is it considered poor practice to use the static keyword in Java on method signatures? If a method performs a function based upon some arguments, and does not require access to fields that are not static, then wouldn't you always want these types of methods to be static?

推荐答案

您可能不希望它是静态的一个原因是允许它在子类中被覆盖.换句话说，行为可能不取决于对象内的数据，而是取决于对象的确切类型.例如，您可能有一个通用的集合类型，带有一个 isReadOnly 属性，该属性在始终可变的集合中返回 false，在始终可变的集合中返回 true不可变集合，并依赖于其他实例变量.

One reason why you may not want it to be static is to allow it to be overridden in a subclass. In other words, the behaviour may not depend on the data within the object, but on the exact type of the object. For example, you might have a general collection type, with an isReadOnly property which would return false in always-mutable collections, true in always-immutable collections, and depend on instance variables in others.

但是，根据我的经验，这种情况很少见 - 通常应该明确指定以保持清晰.通常我会创建一个不依赖于任何静态对象状态的方法.

However, this is quite rare in my experience - and should usually be explicitly specified for clarity. Normally I'd make a method which doesn't depend on any object state static.

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