问题描述
有人能告诉我下面这行副作用"的意思吗?
Could someone tell me the meaning of "side effect" in the following line?
如果您调用一个不返回任何内容的 EL 函数，那么您只是为了它的副作用而调用它.
推荐答案
副作用是方法除了计算和返回值之外所做的任何事情.实例或类字段值的任何更改都是副作用，就像在屏幕上绘制内容、写入文件或网络连接一样.
A side effect is anything a method does besides computing and returning a value. Any change of instance or class field values is a side effect, as is drawing something on the screen, writing to a file or a network connection.
严格来说，函数"被定义为没有副作用——这就是 Java 使用方法"这个词的原因.没有返回值的真正函数将毫无意义.
Strictly speaking, a "function" is defined as not having side effects - which is why Java uses the word "method" instead. A real function with no return value would be pointless.
显然，一个没有返回值的方法必须有某种副作用来证明它的存在是正确的.Set 方法就是一个例子 - 副作用是改变对象的内部状态.
Obviously, a method that does not have a return value must have some sort of side effect that justifies its existence. Set methods are an example - the side effect is changing the object's internal state.
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