在转换的情况下Java编译时错误 [英] Java compile time error in case of casting

问题描述

以下代码给出了编译时错误类型不匹配：无法从int转换为字节

The below code gives me compile time error Type mismatch: cannot convert from int to byte

int i = 10;
byte b = i;

但是下面没有

 final int i = 10;
 byte b = i;

我不明白为什么编译器在最终的情况下表现如何？

I don't understand why compiler is behaving in case of final?

推荐答案

我认为这是因为10适合一个字节，但如果整数超过8位，则无法正常执行这个任务了。

I think it's because 10 fits in a byte, but if the integer was something that takes more than 8 bits then it wouldn't be able to properly do this assignment anymore.

编辑

为了澄清，使其成为最终允许编译器处理int作为常量，因此它可以进行常量折叠。它可能会阻止使用非final int赋值，因为它在编译时不知道该值，并且它可能比字节可以容纳的值大。

To clarify, making it final is allowing the compiler to treat the int as a constant so it can do constant folding. It's probably preventing the assignment with the non-final int because it doesn't know that value at compile time and it could be way bigger than what a byte can hold.

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