java left shift and right shift

Today I reviewed left shift and right shift in java. Here is an example for negative numbers:

Positive and negative numbers are represented in the form of complement in java

For example -2 is represented in the computer as 11111111 11111111 11111111 11111110

1. Shift left

-2<<2 That is, the result of shifting -2 to the left by 2 bits is: 11111111 11111111 11111111 11111000 (the low bits are complemented with 0)

The above is the complement code, and the highest bit is 1 indicating that this is a negative number. The complement of a negative number is obtained by taking the original code of a positive number: "The highest bit is 1, the remaining bits are inverted, and finally 1 is added."

So by inverting, you can know that the result of -2<<2 actually represents the number 10000000 00000000 00000000 00001000 (-8)

2. Shift right

If the high bit is 1, add 1 to the high bit. If it is 0, add 0

-2>>2: 11111111 11111111 11111111 11111111

10000000 00000000 00000000 00000001 (-1)

3. The shift operator can be combined with "=" to use

a< <=2 means that the value after a is shifted to the left by 2 bits and then assigned to a

4. To add: the Java virtual machine shields the big-endian and little-endian problems, and it is all little-endian internally.