Java中ClassCastException的说明 [英] Explanation of ClassCastException in Java

问题描述

我阅读了一些写在"ClassCastException"上的文章，但是我对它的含义一无所知.什么是ClassCastException?

I read some articles written on "ClassCastException", but I couldn't get a good idea on what it means. What is a ClassCastException?

推荐答案

直接来自

抛出该代码以表明试图将对象投射到它不是一个子类实例.

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

例如，当尝试将 Integer 转换为 String 时， String 不是 Integer的子类.，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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