Example code analysis of Java operator

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One: arithmetic operator

1. What are the arithmetic operators

① basic four operators: +-* /%

② incremental assignment operator: + =-= * = / =% =

③ self-increasing / self-subtracting operator + +-

two。 How to use arithmetic operators

Public class TestDemo {public static void main (String [] args) {int aqum8; int bao20; System.out.println (ahumb); / / + System.out.println (bmera); / /-System.out.println (aqqb); / / * System.out.println (bacca); / double cations 8.0; double dudes 17.0 System.out.println (String c); / / 2.125}} public class TestDemo {public static void main (String [] args) {int aplink 10; ajar 10; / equivalent to Atropa 10; amelight 10; / equivalent to ajar 10; aweed 10; / / equivalent to aweed 10; a Universe 2; / / equivalent to athermal 10; a% visa 2 / equivalent to public static void main;}} public class TestDemo {public static void main (String [] args) {int astat20; astatine; + + a; int breadth; int cantilever; System.out.println (a); / / 24 System.out.println (b); / / 22 System.out.println (c); / / 24}}

3. Considerations for arithmetic operators

There is no need to talk about addition and subtraction. First of all, let's talk about two points for attention in division.

A) the int / int result is still int, which needs to be calculated using double, as shown in the above code

B) 0 cannot be used as a divisor, and an error will be reported if 0 is calculated as a divisor

Let's go on to talk about the points for attention in the operation of the surplus:

The remainder symbol can be used to find the module not only for int but also for double.

Double caterpillar Musi 8.0 / double dances17.0 / System.out.println (d% c); / / 1.0

Finally, I would like to talk about two precautions for the self-increment / self-subtraction operator.

A) if you do not take the return value of the expression of the self-increment operation, there is no difference between pre-increment and post-increment.

B) if you take the return value of the expression, the pre-increment is first self-increment and then assignment followed by self-increment.

Two: relational operators

1. What are the relational operators

There are six relational operators: =! = >

< >

= b); System.out.println (a = b);}

3. Considerations for relational operators

The expression return value of the relational operator is of type boolean

Three: logical operators (emphasis)

1. What are the logical operators

Logic and & & logic or | | logic is not!

two。 How to use logical operations

Public class TestDemo {public static void main (String [] args) {int axi10; int bread20; System.out.println (a > b & & ab | | ab)); / / true}}

3. Considerations for logical operators

A) for & &, if the value of the left expression is false, then the overall value of the expression must be false, and there is no need to evaluate the right expression

B) for | |, if the value of the left expression is true, then the overall value of the expression must be true, and there is no need to evaluate the right expression

Four: bit operator

1. What are the bit operators?

The smallest unit of operation on data in Java is not bytes, but binary bits

Bitwise operators include bitwise and & bitwise or | bitwise inverse ~ bitwise XOR ^

two。 How to use the bit operator

Bitwise and &: if both binary bits are 1, the result is 1, otherwise the result is 0

Bitwise or |: if both binary bits are 0, the result is 0, otherwise the result is 1

Bitwise reverse ~: if the bit is 0, it is converted to 1; if the bit is 1, it is converted to 0

Bitwise XOR ^: if the binary bits of two numbers are the same, the result is 0, and if different, the result is 1

3. Considerations for bit operator

Five: shift operation (understanding)

1. What are the shift operators

There are three shift operators: >

two。 How to use the shift operator

Move left: the rightmost position is not needed, the leftmost complement symbol bit (positive complement 0, negative complement 1)

Unsigned move to the right >

3. Considerations for shift operator

A) move 1 bit to the left, equivalent to the original number 2, and move N bits to the left, equivalent to the N power of the original number 2

B) move 1 bit to the right, equivalent to the original number / 2, and move N bits to the right, which is equivalent to the N power of the original number / 2

C) since the shift efficiency of the computer is higher than that of multiplication and division, the shift operation can be used when a code happens to multiply and divide 2 to the N power.

D) it makes no sense to move negative digits or shift too many digits

Six: conditional operator

1. What are the benefits of conditional budget

There is only one conditional operator: expression 1? Expression 2: expression 3

two。 How to use conditional operators

Public class TestDemo {public static void main (String [] args) {int astat10; int biz20; int max=a > bachelorette b; / / 20 System.out.println (max);}}

3. Considerations for conditional operator

When the value of expression 1 is true, the value of the whole expression is the value of expression 2; when the value of expression 1 is false, the value of the whole expression is the value of expression 3

Seven: precedence of operators

The operators are sorted in order of priority: self-addition / subtraction operator, arithmetic operator, comparison operator, logical operator, assignment operator. Please refer to the following table for details:

Sequence

Operator

1.

Parentheses, such as () and []

two。

Unary operators, such as -, +, and!

3.

Arithmetic operators, such as *, /,%, +, and-

4.

Relational operators, such as >, > =,