为什么FileInputStream中的read（）返回一个整数？ [英] Why does the read() in FileInputStream return an integer?

问题描述

这个页面显示说它是这样的当想要指示没有更多字节要读取时，方法可以返回-1。

This page shows says that it is so that the method can return -1 when it wants to indicate that there are no more bytes to be read.

但是一个字节的范围是-128到127，对吧？因为返回一个字节，read（）的返回类型是不是更有意义？

But a byte ranges from -128 to 127, right? And wouldn't it make more sense for the return type of read() to be byte since it returns a byte?

感谢您的时间。

推荐答案

它将值作为 int 返回的原因是它需要返回介于0到255之间的值，以及能够指示何时没有更多字节要从文件中读取。通过使用 int ，您可以返回整个范围的正无符号值0-255，并指示文件何时完成。它不能仅提供这个 byte 值的256个不同值，其中一半是Java默认值为负值。

The reason for it returning the value as an int is that it needs to return a value between 0-255, as well as being able to indicate when there is no more bytes to read from the file. By using an int, you can return the full range of positive unsigned values 0-255, as well as indicate when the file is complete. It wouldn't be able to provide this with only the 256 distinct values of a byte value, half of which are negative by Java default.

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