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First blog address [1]
Interview question manual [2]
Series article address [3]
1. What is a shift operator?
In Java, shift operators are used to perform bit-shift operations on binary numbers. They can shift all the bits of a number to the left or right by a specified number of places.
Java provides three shift operators:
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Left shift operator (<<): Shifts all bits of a number to the left by the specified number of bits, and adds 0 to the low bits. -
Right shift operator (>>): Shifts all bits of a number to the right by the specified number of digits, and fills the high bits with the same value based on the original value of the highest bit. -
Unsigned right shift operator (>>>): Shifts all bits of a number to the right by the specified number of bits, and adds 0 to the high bits.
2. Why is the shift operator needed?
Shift operators are mainly used to process binary data and optimize certain calculation processes. They can quickly perform operations such as multiplication, division, and modulo, and can also be used to set and clear bit masks and bit flags.
3. Implementation principle of shift operator
The implementation principle of the shift operator is based on bit operations of binary numbers. Specifically, the left shift operator (<<) moves all the bits of a number to the left by the specified number of digits, and the right shift operator (>>) moves all the bits of a number to the right by the specified number of digits, and according to The original value of the highest bit is filled with the same value in the high bits. The unsigned right shift operator (>>>) moves all the bits of a number to the right by the specified number of digits and fills the high bits with 0.
4. Examples of using shift operators
Here are some examples of using shift operators:
int a = 10; // 二进制表示为 00001010
// 左移运算符（<<）
int b = a << 2; // 结果为 40，二进制表示为 00101000
// 右移运算符（>>）
int c = a >> 1; // 结果为 5，二进制表示为 00000101
// 无符号右移运算符（>>>）
int d = a >>> 3; // 结果为 1，二进制表示为 00000001
5. Advantages of shift operators
Shift operators have the following advantages:
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Quickly perform operations such as multiplication, division, and modulo. -
Can be used to set and clear bit masks and bit flags. -
Can improve the performance and efficiency of your code in some cases.
6. Disadvantages of shift operators
The main disadvantages of shift operators include:
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容易引起错误，特别是对负数进行右移操作时可能会导致意外结果。 -
不够直观，需要理解二进制数的位操作规则才能正确使用。
7. 移位运算符的使用注意事项
在使用移位运算符时，需要注意以下事项：
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对于有符号的整数类型（如 int），右移运算符（>>）会保留原来最高位的值，并在高位补上相同的值。而无符号右移运算符（>>>）则会在高位补 0。 -
移位操作可能导致溢出或丢失精度，特别是当移动的位数超过了数据类型的范围时。 -
在进行位掩码和位标志的设置与清除时，需要使用适当的移位运算符和位操作技巧。
8. 总结
移位运算符是 Java 中用于对二进制数进行位移操作的工具。它们可以将一个数的所有位向左或向右移动指定的位数，并根据规则在低位或高位补上相应的值。移位运算符主要用于处理二进制数据和优化某些计算过程，但在使用时需要注意溢出、精度丢失和位操作等问题。
参考资料
首发博客地址: https://blog.zysicyj.top/
[2]面试题手册: https://store.amazingmemo.com/chapterDetail/1685324709017001
[3]系列文章地址: https://blog.zysicyj.top/categories/技术文章/后端技术/系列文章/面试题精讲/
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