java - 为什么在 Java 中必须将字节上的按位运算强制转换为字节？

Question

为什么这里需要 Actor 阵容？

byte a = 0b0000_0000;
byte b = (byte) ~a;

a 是一个字节，b 是一个字节...为什么需要转换？

Answer 1

因为Java Language Specification这么说

Unary numeric promotion (§5.6.1) is performed on the operand. The type of the unary bitwise complement expression is the promoted type of the operand.

and

Otherwise, if the operand is of compile-time type byte, short, or char, it is promoted to a value of type int by a widening primitive conversion (§5.1.2).

int 类型的值不能分配给 byte 类型的变量。