移位运算符 - 操作数必须可转换为整数基元？

Question

我正在准备 Java 考试，我正在阅读 "OCA Java SE 8 Programmer Study Guide (Exam 1Z0-808)"。在运算符部分我发现了这句话：

Shift Operators: A shift operator takes two operands whose type must be convertible to an integer primitive.

我觉得很奇怪，所以我用 long 测试了它：

public class HelloWorld{

     public static void main(String []args){
         long test = 3147483647L;
         System.out.println(test << 1);

     }
}

它成功了，没有编译器错误，结果是正确的。这本书有错误还是我误解了书中的引述？

Answer 1

他们使用 integer 不是 Java int 的方式，而是 "integer type instead of floating point or other type"。 Java的long也是一个整数，只是一个64位宽的整数。

Answer 2

移位运算符 >> 和 << 在 JLS section 15.19 中定义。引用:

Unary numeric promotion (§5.6.1) is performed on each operand separately. (Binary numeric promotion (§5.6.2) is not performed on the operands.)

It is a compile-time error if the type of each of the operands of a shift operator, after unary numeric promotion, is not a primitive integral type.

书上说的"integer primitive"其实是在说"primitive integral type"（定义在JLS section 4.2.1）：

The values of the integral types are integers in the following ranges:

For byte, from -128 to 127, inclusive

For short, from -32768 to 32767, inclusive

For int, from -2147483648 to 2147483647, inclusive

For long, from -9223372036854775808 to 9223372036854775807, inclusive

For char, from '\u0000' to '\uffff' inclusive, that is, from 0 to 65535

移位运算符 - 操作数必须可转换为整数基元？

Shift operators - operands must be convertible to an integer primitive?

java

bit-shift

java-8