Java-类方法可以看到相同类参数的私有字段 [英] Java - Class method can see private fields of same-class parameter

问题描述

我遇到了一个很奇怪的行为，不确定是Java问题还是Eclipse的问题.

I'm encountering a rather odd behavior, and not sure if this is a Java issue or just something with Eclipse.

采用以下代码:

class Foo {
  private String text;

  public void doStuff(Foo f) {
    System.out.println(f.text);
  }
}

这里的问题是，为什么f.text可以访问?这是一个私有字段，按照我的逻辑，它不应该是，但IDE似乎认为是.

The problem here is, why is f.text accessible? It's a private field, so by my logic, it shouldn't be, but the IDE seems to think it is.

推荐答案

这是设计使然.在相同的类中，即使在不同的实例中，也可以访问私有字段.请参阅此处，以获取更多详细信息以及Oracle对此的正式声明. .由于doStuff是Foo的成员，因此可以访问Foo的任何私有字段.

This is by design. Private fields are accessible within the same class, even if a different instance. See here for more details and an official statement from Oracle on this. Since doStuff is a member of Foo, any private fields of Foo are accessible for it.

private修饰符指定只能在其自己的类 [甚至从其他实例]中访问该成员. [强调我的]

The private modifier specifies that the member can only be accessed in its own class [even from a different instance]. [emphasis mine]

现在，由于text的可见性修饰符，以下代码示例不起作用:

Now, the following code example does not work due to text's visibility modifier:

class Bar{
  public int baz;
  public void doMoreStuff(Foo f){
    System.out.println(f.text);
  }
}

因为doMoreStuff是在Bar中定义的，而不是在Foo中定义的.

since doMoreStuff is defined in Bar, not Foo.

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