连续多次演员不按预期工作 [英] Multiple casts in succession not working as intended

问题描述

根据我的理解，Casts用于将值从一种类型转换为另一种类型。该程序连续使用三个演员表。

As per my understanding Casts are used to convert a value from one type to another. This program uses three casts in succession.

public class Multicast {
public static void main(String[] args) {
System.out.println((int) (char) (byte) -1);
  }
 }

我认为它会打印-1但它正在打印它打印65535，但为什么？

I thought it will print -1 but it is printing It prints 65535, but why?

推荐答案

表达式：（int）（char）（byte） - 1

1. -1 的类型为int


2. （byte）-1 是一个值为-1的字节


3. （char）（byte）-1 首先将值为-1的字节再次符号扩展为值为-1的32位整数。这意味着所有32位都设置为1（32位的-1的双补码编码）。然后它被转换为类型 char 这是一个无符号的16位值，因此你将16位设置为1，其值为65535。


4. （int）（char）（byte）-1 通过将其再次显式地转换为32位整数，确保将其打印为一个数字而不是代码点65535的字符。

1. -1 is of type int
2. (byte) -1 is a byte with value -1
3. (char) (byte) -1 first the byte with value -1 is sign extended again to be an 32-bit integer of value -1. This means that all the 32-bit are set to 1 (the two-complement encoding of -1 in 32 bits). Then it is cast to the type char which is an unsigned 16-bit value, so you get 16 bits set to one, which has the value 65535.
4. (int) (char) (byte) -1 by explicitly casting it again to a 32-bit integer, you make sure that it is printed as a number instead of the character with the codepoint 65535.

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