The 6th operator of Java from small white to Daniel Lite (top)

Operators (also called operators) in the Java language are very similar in style and functionality to C and C + +. This chapter introduces some of the main operators in the Java language, including arithmetic operators, relational operators, logical operators, bitwise operators, and other operators.

6.1 Arithmetic operators

The arithmetic operators in Java are primarily used to organize arithmetic operations of numeric type data, which can be divided into unary and two-tuple operators, depending on the operand of the participating operation.

6.1.11-dollar operator

There are 3 arithmetic unary operations, namely-, + + and –. See table 6-1 for specific instructions.

Table 6-1 unary arithmetic operations

operator	name	Description	Example
-	take the inverse symbol	negation operation	b =-a
++	add a	First take the value plus one, or first add the value again	a++ or ++a
–			a– or –a

In table 6-1,-A is a negation of a, a++ or a – is a plus or minus one after the expression is finished. The ++a or –a is a plus one or minus one, then the expression operation.

The sample code is as follows:

int a = 12; System.out.println (-a); ①int B = a++; ②system.out.println (b); b = ++a; ③system.out.println (b); 1234567

The output results are as follows:

-1212141234

The above code ① line is-A, the A variable is reversed, the result output is-12. The first line of ② code is to assign a value to the B variable plus one, that is, the first assignment after + +, so the output is 12. The ③ line code is to add a plus one, and then assign a to the B variable, that is, the first + + after the assignment, so the output is 14.

6.1.22-dollar operator

Binary operators include: + 、-、 *,/, and%, which are valid for numeric type data, see table 6-2 for details.

Table 6-2 Two-dollar arithmetic operations

operator	name	Description	Example
+	Add	The and of a plus B can also be used for string types, strings join operations	A + b
-	Reducing	Find the difference between a minus B	A-B
*	By	The product of a multiplied by B	A * b
/	Except	The quotient of a divided by B	A/b
%	Take surplus	To find the remainder of a divided by B	A% b

The sample code is as follows:

Declares a character-type variable char charnum =  ' A ';     //  declares an integer-type variable int  intresult = charnum + 1;             ①system.out.println (intresult);intresult = intresult - 1; System.out.println (intresult);intresult = intresult * 2; System.out.println (intresult);intresult = intresult / 2; System.out.println (intresult); Intresult = intresult + 8;intresult = intresult  % 7; System.out.println (Intresult); System.out.println ("-------");//  declares a floating-point variable double doubleresult = 10.0; System.out.println (doubleresult);d oubleresult = doubleresult - 1; System.out.println (doubleresult);d oubleresult = doubleresult * 2; System.out.println (doubleresult);d oubleresult = doubleresult / 2; System.out.println (doubleresult);d Oubleresult = doubleresult + 8;doubleresult = doubleresult % 7; System.out.println (Doubleresult); 12345678910111213141516171819202122232425262728293031323334353637

The output results are as follows:

6665130653-------10.09.018.09.03.0123456789101112

In the above example, the numeric type data is two-dollar operation, where code ① will be the character type variable charnum and the integer type of the addition operation, participate in the operation of the character (' A ') of the Unicode encoding 65. The other code is relatively simple no longer repeat.

6.1.3 Arithmetic assignment operator

The arithmetic assignment operator is a shorthand, typically used for changes in the variables themselves, as described in table 6-3.

Table 6-3 arithmetic Assignment characters

operator	name	Example
+=	Add Value	A + = B, a + = B+3
-=	Reduced assignment value	A-= b
*=	Multiply Assign Value	A *= b
/=	In addition to assigning values	A/= b
%=	Assignment of residual value	A%= b

The sample code is as follows:

int a = 1;int b = 2;a += b;     //  equivalent to  a = a + bsystem.out.println (a);a += b + 3; //  equivalent to  a = a + b + 3system.out.println (a);a -= b;      //  equivalent to  a = a - bsystem.out.println (a);a *= b;      //  equivalent to  a=a*bsystem.out.println (a); a /= b;     / /  equivalent to  a=a/bsystem.out.println (a);a %= b;     //  equivalent to  a=a %bsystem.out.println (a); 123456789101112131415161718 

The output results are as follows:

38612601234567

The above examples respectively for the integral type of + =,-=, *=,/= and%= operations, the specific statements are not described.

6.2 Relational operators

A relational operation is an operation that compares two expression-size relationships, which results in Boolean-type data, which is true or false. There are 6 types of relational operators: = =,! =, >, <, >=, and <=, see table 6-4 for details.

Table 6-4 Relational operators
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* * prompt = = and! = can be applied to base data types and reference types. When used for reference type comparisons, the comparison is whether two references point to the same object, but in most cases the actual development process is comparing the content of the object to the same object, rather than comparing it.
**
The sample code is as follows:

int value1 = 1;int value2 = 2;if  (value1 == value2)  {     system.out.println ("Value1 == value2");} if  (value1 != value2)  {    system.out.println ("value1 !=  Value2 ");} if  (value1 > value2)  {    system.out.println ("value1 >  value2 ");} if  (value1 < value2)  {    system.out.println ("value1 <  value2 ");} if  (value1 <= value2)  {    system.out.println ("value1 <=  value2 ");} 1234567891011121314151617181920212223 

The results of the run program output are as follows:

Value1! = value2value1 < value2value1 <= value21234

6.3 Logical operators

The logical operator is to operate on a Boolean variable, and the result is a Boolean type, as described in table 6-5.

Table 6-5 logical operators
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Tips Short circuit with (&&) and short circuit or (| | Can be used to optimize the calculation method, thereby improving efficiency. In the actual programming, the use of short-circuit and short-circuit or should be given priority.

The sample code is as follows:

int i = 0;int a = 10;int b = 9;if  ((a > b)  | |   (i == 1)  {                           ①     System.out.println ("or arithmetic is   true");}  else {    system.out.println ("or operation is   false");} if  (a < b  &&  (i == 1))  {                       ②     system.out.println ("and arithmetic for   true");}  else {    system.out.println ("with arithmetic for   false");} if  ((a > b)  | |   (a++ == --b)  {                   ③    system.out.pRintln ("a = "  + a);     system.out.println ("b = "  + &NBSP;B);} 1234567891011121314151617181920

The above code runs the output as follows:

Or the operation is true and the operation is false 123

Where the ① line of code for short-circuit calculation, because (a > B) is true, the subsequent expression (i = = 1) is no longer evaluated, the output is true. Similarly, the ② Line code is also shorted, since (a < b) is false, the subsequent expression (i = = 1) is no longer evaluated and the result of the output is false.

The code in line ③ in the conditional expression doped with + + and-operation, because (a > B) is true, the subsequent expression (a++ ==–b) is no longer evaluated, so the last is a = ten, B = 9. If you put a short circuit or (| | ) to Logical OR (|), the result of the output is a = one and B = 8.

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The 6th operator of Java from small white to Daniel Lite (top)