“ClassCastException”的解释在Java中 [英] Explanation of "ClassCastException" in Java

问题描述

我阅读了一些关于ClassCastException的文章，但我无法对此有所了解。是否有一篇好文章或什么是简短的解释？

I read some articles written on "ClassCastException", but I couldn't get a good idea on that. Is there a good article or what would be a brief explanation?

推荐答案

直接来自 ClassCastException ：

抛出以表明代码有
试图将对象强制转换为
子类它不是
实例。

Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance.

因此，例如，当一个人试图投出一个整数到字符串，字符串不是的子类整数，因此将抛出 ClassCastException 。

So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be thrown.

Object i = Integer.valueOf(42);
String s = (String)i;            // ClassCastException thrown here.

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