August 2021
Intermediate to advanced
450 pages
4h 46m
Chinese
Content preview from 面向对象的思考过程（原书第5版）Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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3.1.5 设计构造函数
我们已经看到了，设计类的一个最佳实践是初始化所有属性。有些语言中，编译器会提供一部分初始化工作。与往常一样，不要依赖编译器来初始化属性！在Java中，只有属性被初始化后你才能使用它。如果属性在代码中很靠前，请确保你初始化属性为一些有效值，比如设置整数为0。
构造函数用来确保应用程序处于稳定的状态（我喜欢称之为“安全”的状态）。例如，如果把属性作为除法运算中的分母，那么初始化该属性为0会导致应用程序崩溃。你必须考虑除法中用0作为除数是非法操作。始终初始化属性为0并不总是最好的方式。
在设计时，优秀的实践应该是为所有属性确定一个稳定的状态，然后在构造函数中初始化这些属性为稳定的状态。
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