Then brother combed the Java Knowledge Point-Operator (v)

Operator: is a special symbol used to represent the operation, assignment, and comparison of data.

1. Arithmetic operators (+ 、-、 *,/,%, + + 、--)

　　A) In addition to:

int i =n; int j = i/5;            // 2 double d1 = I/5;        // 2.0 double d2 = (double) i/5;  // 2.4 double d3 = i/5.0;        // 2.4　　　　　　　　　　　　

b) difference between front + + and after + +

Before + +: Add a value to yourself first, then do the operation assignment

After + +: Do the arithmetic assignment, then add a value to yourself

int a = ten;  int//a=11 b=11       int//a=11 c=10

The increment and decrement operators can only be used for operation variables and cannot be used directly to manipulate values or constants! For example, 5++, 8--and so on are wrong!

2. Assignment operators (+ =,-=, *=,/=,%=, =)

int i = ten+ = 3; // The result of the operation equals i = i + 3;

The result of the i+=3 operation is equivalent to i = i + 3, but there are some differences.

For example:

 Short s = ten// Compile error s + = 3;    // the operation can be implemented without changing the data type of S

"Knowledge points": assignment operations + =,-=,/=,%= are performed but do not change the data type of the variable

Written questions:

1, the evaluation assignment operator uses

int A = 1*= 0.1;       System.out.println (a); // 0       a++;       System.out.println (a); // 1

　　　　2, the difference between the examination = and = =

Boolean false　　　　;  if (b==true) {System.out.println ("= = result is true")       ;       } Else {           System.out.println ("= = result is false")       ;       } if (b=true) {           System.out.println ("= result is true");       }        Else {           System.out.println ("= result is false");       }

Output Result:

= = result is False
= result is True

3, comparison operators (= =,!) =, <, >, <=, >=, instanceof)

　　The result of the comparison operator is a Boolean type

4, logical operators (&-logic and, &&-short circuit and, | | -Short circuit or 、!-logic non-, ^-logic XOR)

A) The variables on the left and right side of the logical operator are Boolean.

b) The results of & and && are identical, | and | | The results are identical.

c) What is the difference between & and &&?

&: Regardless of whether the left is true or false, the right side will operate.

&&: When the left side is false, then the right side does not operate.

So as long as there is false on the left there is a difference, if it is true, it is identical.

Of course, we definitely recommend && in the process of development, which can reduce the overhead of right-side operation.

| and | | The difference is no longer elaborated the same idea.

c) XOR, as the name implies, returns True when A and B are inconsistent, and returns false.

5, bitwise operators (<<, >>, >>>, &, |, ^, ~)

　　A) << left shift (several left, followed by 0)

3<<2 = 3*2*2=12

0000 0000 0000 0011 = 3

0000 0000 0000 1100 = 2 of 3 times + 2 of 2-square = 12

b) >> right shift (right shift several, the front needs to see whether the first bit is 0 or 1, if 1 is used 1 to complement, if 0 is used 0 to complement)

31>>2 = 7

c) >>> unsigned Right shift (right shift several, front whether the first bit is 0 or 1, all with 0 to complete)

31>>>2 = 7

d) & is with operations.

E) | is different or calculated

f) ^ xor

In the case of variable type conversions, swap the values of a and B without declaring a third-party variable. Using the Xor method is absolutely perfect.

int a = 10;

int b = 15;

Answer:

A = a ^ b;

b = a ^ b;

A = a ^ b;

6, ternary operator (?) :）

Used to complete simple selection logic, which is to select one of the two choices according to the condition.

　(conditional expression)? Expression 1: Expression 2

If the expression 1 and expression 2 must be of the same type of data type

Then brother combed the Java Knowledge Point-Operator (v)