为什么要使用getter和setter / accessors？ [英] Why use getters and setters/accessors?

问题描述

使用getter和setter有什么好处 - 只能获取和设置 - 而不是简单地为这些变量使用公共字段？

What's the advantage of using getters and setters - that only get and set - instead of simply using public fields for those variables?

如果getter和setter一直在做不仅仅是简单的获取/设置，我可以非常快地计算出这个，但我不是100％明确如何：

If getters and setters are ever doing more than just the simple get/set, I can figure this one out very quickly, but I'm not 100% clear on how:

public String foo;

更糟糕的是：

private String foo;
public void setFoo(String foo) { this.foo = foo; }
public String getFoo() { return foo; }

前者需要更少的样板代码。

Whereas the former takes a lot less boilerplate code.

推荐答案

实际上有许多好的理由考虑使用访问者而不是直接暴露类的字段 - 超出了封装的论点和使未来的变化更容易。

There are actually many good reasons to consider using accessors rather than directly exposing fields of a class - beyond just the argument of encapsulation and making future changes easier.

以下是我所知道的一些原因：

• 封装与获取或设置属性相关的行为 - 这样可以在以后更轻松地添加其他功能（如验证）。


• 隐藏属性的内部表示形式使用替代表示公开属性时。


• 保护公共接口免受更改 - 允许公共接口在实现更改时保持不变，而不会影响现有使用者。


• 控制属性的生命周期和内存管理（处理）语义 - 在非托管内存环境（如C ++或Objective-C）中尤为重要。


• 提供调试拦截指向属性在运行时更改的时间 - 在某些语言中调试属性更改为特定值的时间和位置可能非常困难。


• 已改进设计用于对属性getter / setter进行操作的库的互操作性 - 脑海中浮现出模拟，序列化和WPF。


• 允许继承者更改属性的行为和暴露的语义覆盖getter / setter方法。


• 允许getter / setter作为lambda表达式而不是值传递。


• getter和setter可以允许不同的访问级别 - 例如，获取可能是公共的，但该组可能受到保护。

• Encapsulation of behavior associated with getting or setting the property - this allows additional functionality (like validation) to be added more easily later.
• Hiding the internal representation of the property while exposing a property using an alternative representation.
• Insulating your public interface from change - allowing the public interface to remain constant while the implementation changes without affecting existing consumers.
• Controlling the lifetime and memory management (disposal) semantics of the property - particularly important in non-managed memory environments (like C++ or Objective-C).
• Providing a debugging interception point for when a property changes at runtime - debugging when and where a property changed to a particular value can be quite difficult without this in some languages.
• Improved interoperability with libraries that are designed to operate against property getter/setters - Mocking, Serialization, and WPF come to mind.
• Allowing inheritors to change the semantics of how the property behaves and is exposed by overriding the getter/setter methods.
• Allowing the getter/setter to be passed around as lambda expressions rather than values.
• Getters and setters can allow different access levels - for example the get may be public, but the set could be protected.

这篇关于为什么要使用getter和setter / accessors？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！