java – 构造函数何时以及如何对实例变量强制实施限制？

我是编程的新手,我正在学习Java作为我的第一个oo语言,通过David J. Eck编写的Java编程简介和卡住的论坛帖子.

我的问题可以被认为是Java Class Constructor Parameters with range limits的后续,它涉及将Hour类的构造函数的int参数限制为0到23.

上述问题的答案提到抛出Instantiation Exception或IllegalArgumentException,但不清楚哪个是更好的样式.

此外,如果有的话,与验证代码相关的开销是否合理？

解决方法:

抛出IllegalArgumentException只是正确的.

Thrown to indicate that a method has been passed an illegal or inappropriate argument.

InstantiationException用于不同的目的.

Thrown when an application tries to create an instance of a class using the newInstance method in class Class, but the specified class object cannot be instantiated. The instantiation can fail for a variety of reasons including but not limited to:

• the class object represents an abstract class, an interface, an array class, a primitive type, or void

• the class has no nullary constructor

InstantiationException与无法调用构造函数的反射调用有关,但是IllegalArgumentException意味着成功调用了构造函数(或方法),但代码块确定参数不合适.

最好有一点开销来验证进入构造函数(和方法)的参数.一个不能正常工作的程序或类比一个正常工作的程序更糟糕,并且可能会慢得忽视.

标签：java,oop,methods,contracts
来源： https://codeday.me/bug/20190624/1277738.html