如何指定常量是字节还是短？ [英] How to specify a constant is a byte or short?

问题描述

对于long数据类型，我可以用L后缀一个数字，以使编译器知道它很长。字节和短字怎么样？

For the long data type, I can suffix a number with L to make the compiler know it is long. How about byte and short?

作为动机，以下产生类型不匹配错误：

As motivation, the following yields a type-mismatch error:

List<Short> a = Arrays.asList(1, 2, 3, 4);

推荐答案

你实际谈论的是一个整数 literal （ 1 ）与长文字（ 1L ）。 Java中实际上没有短文本或字节文字。但通常并不重要，因为存在从整数文字到类型 byte 的隐式转换， short 和 char 。因此：

What you are actually talking about is an integer literal ( 1 ) versus a long literal ( 1L ). There is actually no such thing as a short or byte literal in Java. But it usually doesn't matter, because there is an implicit conversion from integer literals to the types byte, short and char. Thus:

final byte one = 1;  // no typecast required.

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隐式转换仅在字面值为在要求的范围内。如果不是你需要一个类型演员;例如。

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The implicit conversion is only allowed if the literal is in the required range. If it isn't you need a type cast; e.g.

final byte minusOne = (byte) 255;  // the true range of byte is -128 .. +127

还有其他一些明确的情况需要转换;例如消除方法重载的歧义，或强制表达式中的特定解释。在这种情况下，您需要使用强制转换进行转换。

There are other cases where an explicit conversion is needed; e.g. to disambiguate method overloads, or to force a specific interpretation in an expression. In such cases you need to use a cast to do the conversion.

您的示例是另一种情况。

Your example is another of those cases.

但最重要的是，没有用于表达 byte 或 short的Java语法文字。

But the bottom line is that there is no Java syntax for expressing byte or short literals.

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