Java Operators

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));
　　}
}

The compiled and run results of the above examples are as follows:

a == b = false
a != b = true
a > b = false
a < b = true
b >= a = true
b <= a = false

Bitwise operators

Java defines bitwise operators that are applied to integer types (int), long types (long), short types (short), character types (char), and byte types (byte) and other types.

Bitwise operators operate on all bits and perform bitwise operations. Assuming a = 60, b = 13;Their binary format representation will be as follows:

A = 0011　1100
B = 0000　1101
-----------------
A&B = 0000　1100
A | B = 0011　1101
A ^ B = 0011　0001
~A=　1100 0011

The following table lists the basic operations of bitwise operators, assuming the integer variable A has the value 6The value of variable B is 13:

Example

The following simple example program demonstrates bitwise operators. Copy and paste the following Java program and save it as Test.java file, then compile and run this program:

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 );
　
　　　　　c = a ^ b;　　　　　　　/*　49　= 0011　0001　*/
　　　　　System.out.println("a ^ b = \　+　c );
　
　　　　　c = ~a;　　　　　　　　　　/*-61　=　1100 0011　*/
　　　　　System.out.println("~a = \　+　c );
　
　　　　　c = a <<　2;　　　　　/*　240 =　1111　0000　*/
　　　　　System.out.println("a <<　2　= \　+　c );
　
　　　　　c = a >>　2;　　　　　/*　15　=　1111　*/
　　　　　System.out.println("a >>　2　　= \　+　c );
　　
　　　　　c = a >>>　2;　　　　　/*　15　= 0000　1111　*/
　　　　　System.out.println("a >>>　2　= \　+　c );
　　}
}

The compiled and run results of the above examples are as follows:

a & b =　12
a | b =　61
a ^ b =　49
~a =　-61
a <<　2　=　240
a >>　2　　=　15
a >>>　2　=　15

Logical operators

The following table lists the basic operations of logical operators, assuming that the boolean variable A is true and variable B is false

Example

The following simple example program demonstrates logical operators. Copy and paste the following Java program and save it as Test.java file, then compile and run this program:

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));
　　}
}

The compiled and run results of the above examples are as follows:

a && b = false
a || b = true
!(a && b) = true

Short-circuit logical operators

When using logical operators, the result is true only when both operands are true, but when the first operand is false, the result is definitely false, and the second operand will no longer be judged at this time.

public class Logic{}}
　　　　public static void main(String[] args){
　　　　　　　　int a =　5;//Define a variable;
　　　　　　　　boolean b = (a<4)&&(a++<10);
　　　　　　　　System.out.println("The result of using the short-circuit logical operator is"+b);
　　　　　　　　System.out.println("The result of a is"+a);
　　　　}
}

The output result is:

The result of using the short-circuit logical operator is false
The result of a is5

Analysis:This program uses the short-circuit logical operator (&&), first判断 a<4 The result is false, then the result of b must be false, so the second operation a is no longer executed++<10 judgment, so the value of a is 5.

Assignment operator

The following are the assignment operators supported by the Java language:

Example

The following simple example program demonstrates the assignment operator. Copy and paste the following Java program and save it as AssignmentOperator.java file, then compile and run this program:

class AssignmentOperator {
　　　　public static void main(String[] args) {
　　　　　　　　
　　　　　　　　int number1, number2;
　　　　　　　　
　　　　　　　　//Assign5to number1
　　　　　　　　number1　=　5;
　　　　　　　　System.out.println(number1);
　　　　　　　　　　　　　　　　
　　　　　　　　//Assign the variable number2is assigned to number1
　　　　　　　　number2　= number1;
　　　　　　　　System.out.println(number2);
　　　　}
}

The compiled and run results of the above examples are as follows:

5
5

Conditional operator (?:)

The conditional operator is also known as the ternary operator. This operator has3An operand, and it needs to determine the value of the boolean expression. The main purpose of this operator is to decide which value should be assigned to the variable.

variable x = (expression) ? value if true : value if false

Example

public class Test {
　　　public static void main(String[] args){
　　　　　　int a, b;
　　　　　　a =　10;
　　　　　　//　If a is equal to　1　If it is true, set b to　20, otherwise it is　30
　　　　　　b = (a ==　1)?　20 :　30;
　　　　　　System.out.println("Value of b is:");　+　　b);
　
　　　　　　//　If a is equal to　10　If it is true, set b to　20, otherwise it is　30
　　　　　　b = (a ==　10)?　20 :　30;
　　　　　　System.out.println("Value of b is:");　+　b);
　　　}
}

The compiled and run results of the above examples are as follows:

Value of b is :　30
Value of b is :　20

The instanceof operator

This operator is used to operate on object instances and check whether the object is of a specific type (class type or interface type).

The format of the instanceof operator is as follows:

(Object reference variable) instanceof (class/interface type)

If the object referred to by the variable on the left side of the operator is a class or interface (class/If an object of an interface is on the right side, the result is true.

Here is an example:

String name = "James";
boolean result = name instanceof String;　//　Since name is of type String, it returns true

If the object being compared is compatible with the type on the right, the operator still returns true.

See the following example:

class Vehicle {}
　
public class Car extends Vehicle {
　　　public static void main(String[] args){
　　　　　　Vehicle a = new Car();
　　　　　　boolean result = a instanceof Car;
　　　　　　System.out.println(result);
　　　}
}

The compiled and run results of the above examples are as follows:

true

Java operator precedence

When multiple operators appear in an expression, which one comes first? This involves the issue of operator precedence. Different operator precedence in a multi-operator expression can lead to greatly different results.

For example，（1+3) + (3+2)*2, if this expression is calculated with the plus sign as the most prioritized, the answer would be 18, if the multiplication operator is the most prioritized, the answer would be 14.

Again, x = 7 + 3 * 2; here x gets13, not20, because the multiplication operator has a higher priority than the addition operator, so it is calculated first3 * 2Get6, and then add7.

The operators with the highest priority in the table are at the top, and the lowest priority are at the bottom.