java - 重新抛出前面的 catch block 中处理的异常

Question

在 Oracle 官方网站上写入 (http://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html#rethrow)

In detail, in Java SE 7 and later, when you declare one or more exception types in a catch clause, and rethrow the exception handled by this catch block, the compiler verifies that the type of the rethrown exception meets the following conditions:

-The try block is able to throw it.

-There are no other preceding catch blocks that can handle it.

-It is a subtype or supertype of one of the catch clause's exception parameters.

请专注于第二点(前面没有其他 catch block 可以处理它。)

研究以下代码:

static private void foo() throws FileNotFoundException  {
        try {
            throw new FileNotFoundException();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            throw e;
        }
    }

这段代码编译良好。根据我的观点，在阅读上述文章的引用后，我希望看到编译器会验证它，并且我会收到编译器错误。

我是否理解错了第二点？

Answer 1

这完全没问题，因为 FileNotFoundException 是从 IOException 派生的，并且因为您从不太具体到更具体，所以不应该有任何问题。

<小时/>

编辑:

static private void foo() throws FileNotFoundException  {
    try {
        throw new FileNotFoundException();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (FileNotFoundException e) {
        throw e;
    }
}