Java Operators
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One of the most basic use of a computer is to perform mathematical operations, as a computer language, Java provides a rich set of operators to manipulate variables. We can put the operator into the following groups:
- Arithmetic Operators
- Relational Operators
- Bitwise Operators
- Logical Operators
- Assignment Operators
- Other Operators
First, arithmetic operators
Role and function of arithmetic operators as in mathematics.
| Operators | description |
|---|---|
| + | addition |
| - | Subtraction |
| * | multiplication |
| / | division |
| ％ | Modulo (remainder) |
| ++ | Self-energizing - the operand value is incremented by 1 |
| – | Decrement - reducing the value of the operand 1 |
Example:
public class Test {
public static void main(String args[]) {
int a = 10;
int b = 20;
int c = 25;
int d = 25;
System.out.println("a + b = " + (a + b) );
System.out.println("a - b = " + (a - b) );
System.out.println("a * b = " + (a * b) );
System.out.println("b / a = " + (b / a) );
System.out.println("b % a = " + (b % a) );
System.out.println("c % a = " + (c % a) );
System.out.println("a++ = " + (a++) );
System.out.println("a-- = " + (a--) );
// 查看 d++ 与 ++d 的不同
System.out.println("d++ = " + (d++) );
System.out.println("++d = " + (++d) );
}
}
---结果：
a + b = 30
a - b = -10
a * b = 200
b / a = 2
b % a = 0
c % a = 5
a++ = 10
a-- = 11
d++ = 25
++d = 27
Second, relational operators
| Operators | description |
|---|---|
| == | If the values of the two operands are equal, it is equal condition is true. |
| != | If the value of the operands are not equal, not equal condition is true. |
| > | If the value of the left operand is greater than right operand value, then the condition is true. |
| < | If the value of the left operand is less than right operand value, then the condition is true. |
| > = | If the value of the left operand is greater than or equal to right operand, then the condition is true. |
| <= | If the value of the left operand is less than or equal to right operand, then the condition is true. |
Example:
public class Test {
public static void main(String args[]) {
int a = 10;
int b = 20;
System.out.println("a == b = " + (a == b) );
System.out.println("a != b = " + (a != b) );
System.out.println("a > b = " + (a > b) );
System.out.println("a < b = " + (a < b) );
System.out.println("b >= a = " + (b >= a) );
System.out.println("b <= a = " + (b <= a) );
}
}
---结果：
a == b = false
a != b = true
a > b = false
a < b = true
b >= a = true
b <= a = false
Third, the bitwise operator
| Operators | description | example |
|---|---|---|
| ＆ | Bitwise AND operator, if and only if this bit is a bit in both operands are non-zero only when the result is 1. | (A & B), to give 12, i.e., 0000 1100 |
| | | Bitwise OR operator, as long as a bit of the two operands have a non-zero result when this bit is set to 1. | (A | B) to give 61, i.e., 0011 |
uncommonly used:
| Operators | description | example |
|---|---|---|
| ^ | Bitwise XOR operator, a bit of the two operands are not the same result when the bit is set to 1. | (A ^ B) to give 49, i.e., 00,110,001 |
| 〜 | Bitwise complement operator inverted every operand. | (~ A) -61 obtained, i.e., 11,000,011 |
| << | Bitwise left shift operator. Bitwise left left operand right operand the specified number of digits. | A << 2 to give 240, i.e. 11,110,000 |
| >> | Bitwise right shift operator. The left operand by the right operand bits specify the right number of digits. | I.e., obtain 15 A >> 2 1111 |
| >>> | Zero padding bit right shift operator. The median value of the left operand specified by the operand right RIGHT movement resulting vacancy is filled with zeros. | I.e., obtain 15 A >>> 2 0000 1111 |
Example: **
public class Test {
public static void main(String args[]) {
int a = 60; /* 60 = 0011 1100 */
int b = 13; /* 13 = 0000 1101 */
int c = 0;
c = a & b; /* 12 = 0000 1100 */
System.out.println("a & b = " + c );
c = a | b; /* 61 = 0011 1101 */
System.out.println("a | b = " + c );
}
}
---结果：
a & b = 12
a | b = 61
Fourth, the logical operators
versus
| Conditions 1 condition1 | Conditions 2 condition2 | value |
|---|---|---|
| 1 | 1 | 1 |
| 1 | 0 | 0 |
| 0 | 1 | 0 |
| 0 | 0 | 0 |
or
| Conditions 1 condition1 | Conditions 2 condition2 | value |
|---|---|---|
| 1 | 1 | 1 |
| 1 | 0 | 1 |
| 0 | 1 | 1 |
| 0 | 0 | 0 |
non-
| Conditions 1 condition1 | value |
|---|---|
| 1 | 0 |
| 0 | 1 |
public class Test {
public static void main(String args[]) {
boolean a = true;
boolean b = false;
System.out.println("a && b = " + (a&&b));
System.out.println("a || b = " + (a||b) );
System.out.println("!(a && b) = " + !(a && b));
}
}
---结果：
a && b = false
a || b = true
!(a && b) = true
Differences and ||, & and && in |
Logical operators have expressed
Short circuit the left operator && is false, not required to judge the genuineness of a direct result of the right false operation does not continue
|| shorting operator true left and right ends no further operation will not continue operation result is true
Fifth, the assignment operator
| Operators | description |
|---|---|
| = | Simple assignment operator, the value of the right operand assigned to the left operand |
| + = | Was added and assignment operator, and that the left operand right operand assigned to the left operand addition |
| - = | Save and assignment operator that the left and right operand subtraction operand assigned to the left operand |
| * = | And assignment operator by which the left and right operand multiplication operand assigned to the left operand |
| / = | And assignment operator except that the left and right operands operand division assigned to the left operand |
| （％）= | And assignment modulo operator that the left and right operand operand assigned to the left operand modulo |
uncommonly used:
| Operators | description |
|---|---|
| << = | Left-shift assignment operator |
| >> = | Right shift assignment operator |
| ＆= | Bitwise AND assignment operator |
| ^ = | Bitwise XOR assignment operator |
| | = | Bitwise OR assignment operator |
public class Test {
public static void main(String args[]) {
int a = 10;
int b = 20;
int c = 0;
c = a + b;
System.out.println("c = a + b = " + c );
c += a ;
System.out.println("c += a = " + c );
c -= a ;
System.out.println("c -= a = " + c );
c *= a ;
System.out.println("c *= a = " + c );
a = 10;
c = 15;
c /= a ;
System.out.println("c /= a = " + c );
a = 10;
c = 15;
c %= a ;
System.out.println("c %= a = " + c );
}
}
---结果：
c = a + b = 30
c += a = 40
c -= a = 30
c *= a = 300
c /= a = 1
c %= a = 5
Sixth, the conditional operator (? :)
Conditional operator is also called ternary operator. The operator has three operands, and needs to determine the Boolean expressions.
condition? Results 1: 2 results;
Result of the condition must be boolean, true, false;
public class Test {
public static void main(String args[]){
int a , b;
a = 10;
b = (a == 1) ? 20: 30;
System.out.println( "Value of b is : " + b );
}
}
---结果：
Value of b is : 30
Conditions can be complex
boolean conditionOne = 5>3;
boolean conditionTwo = 5>2;
boolean conditionThree = 5>3;
int num = (conditionOne && (conditionTwo || conditionThree)) ? 1 : 2;
Seven, operator precedence
I tried to write a pithy formula:
Monocular relationship multiplication and division, logical trinocular after the assignment.
Monocular: unary + - (negative) ++ - like
multiplication and division: arithmetic unary * /% + -
is: displacement unary operator << >>
relationships: unary> <> = <= ==! =
logical: logical unary & | ^ && ||!
trinocular: trinocular unary A> B X: Y?
after: meaningless, Minato words only for
Assignment: Assignment =
