Shift operation methods in java (<<, >>, >>>)

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160fe1982d09ca789a82186ac278f907>, signed right shift, shifts the entire binary number of the operand to the right by a specified number of digits, pads the high bits of integers with 0, and pads the high bits of negative numbers with 1 (keeping the sign of negative numbers unchanged).

int rightShift = 10;
System.out.println("十进制:" + rightShift + ", 二进制:" + Integer.toBinaryString(rightShift));
int newRightShift = rightShift >> 2;
System.out.println("右移2位后十进制:" + newRightShift + ", 右移2位后二进制" + Integer.toBinaryString(newRightShift));  //右移n位后的运算数x十进制结果，x = x / 2

The above are positive integers, and the operation results are as follows.

Next, let’s look at what happens when a negative number is shifted right by 2 bits. The result of the operation is as follows.

The basic principle of signed right shift of negative numbers is still the same as left shift. The difference is the calculation of the result, because this is a signed right shift, and the last one is always shifted to the right. The result will be -1. To sum up, if the operand is an even number, then its operation result is x = -(|x| / 2). If the operand is an odd number, then its operation result is x = -(|x| / 2) - 1.

>>>, unsigned right shift, no matter positive or negative, the high bits are filled with 0 (ignoring the sign bit)

Look at the positive numbers first, the positive numbers >>>The calculation results of unsigned right shift and >>signed right shift are the same

int rightShift = 10;
System.out.println("十进制:" + rightShift + ", 二进制:" + Integer.toBinaryString(rightShift));
int newRightShift = rightShift >>> 2;
System.out.println("右移2位后十进制:" + newRightShift + ", 右移2位后二进制" + Integer.toBinaryString(newRightShift));  //右移n位后的云算数x十进制结果，x = x / 2

The above are positive integers, and the operation results are as follows.

Next, let’s look at negative integers. The operation results are as follows.

Although the binary after unsigned shift and the binary after signed shift look the same, the results are quite different. Remember the signed right shift operation, in fact The above is an arithmetic operation that ignores signs, that is, the high bits are uniformly filled with 0.

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