Java Basics-Operators (03)

Concept:

Operator: is the symbol that operates on constants and variables.

Expressions: Java-syntactically-compliant formulas that are concatenated with operators, and expressions that are joined by different operators are expressions of different types.

Operator Classifications:

Arithmetic operator (+-*/% + +--)

Assignment operator (= + = = *=/=)

Relational operators (==,!=,>,>=,<,<=)

Logical operators (&,|,!, ^,&&,| | ）

Ternary operators

Arithmetic operators

Dividing integers can only get integers. to get a decimal, you must have a floating-point number to participate in the Operation .

The character participates in the addition operation (the pure numeric value for the addition operation, which contains the string for the character connection, char->int->string), is actually the character stored in the computer data values (ASCII code table) To participate in the operation.

' A '    , ' a '    , ' 0 '    ,int A =10; char c = ' A '; System.out.println (a+c);    // The result is

Arithmetic operator + +--a small problem. is calculated from left to right and then left-assigned value

int x = 4; int x2 = 4; int y = (x--) + (--x) + (x*10);      // The 4+2+20=26 (x--) value is 4,x 3, and then the (--x) value is 2,x 2; int y2 = (--x2) + (x2--) + (x2*10);  // The 3+3=26 (--x2) value is 3,x2 3, and then the (x2--) value is 3,x2 2; // x = 2,y = 26,y2 =

Arithmetic operator + +--the sinkhole in

int a=1,b=0;    b=a++;     // The first assignment and then the self-addition operation of this procedure results in, b=1,a=2   int a=1;    A=a++;    // a first assigns the value to oneself is 1, then A and then adds 1 This procedure result to be, a=1, very strange has the wood to have the???

Here is the knowledge of the operating system, simply say: Our usual variables and objects are in memory open a piece of memory. And the operation is only CPU-capable. The hole in this topic is a value assigned to the self-added moment of the operation only in the CPU, the result of the calculation exists in the register, is not assigned to an in-memory variable.

It can also be understood as: The assignment operator is to store the results of the CPU registers in memory;

Assignment operations

Basic Replication operators: =

Extended assignment Operator: + = = *=/= ...

+ = Take the left and right data to do +, then assign the result to the left

Note: The extended assignment operator, which implicitly enforces type conversions, forces the type to the left of the type

For example: variable a,a+=10; equivalent to a= (data type of a) (A+10);

Relational operators

==,!=,>,<,>=,<=

The result of the relational operator is a Boolean type.

logical operators

The logical operator is the one used to connect the relationship expression

&,|,!, ^ (XOR or the same false, different true, can be understood as a couple relationship, the same sex is not a couple, sex is different from the couple)

&& (as with & results), | | (As with | results)

Ternary operators

Relationship expressions? Expression 1: Expression 2

A. Evaluates the value of the relationship expression to see if it is true or false B. If true, expression 1 is the result; if false, Expression 2 is the result

 Shorts = 30; inti = 50; //s = i+s; //error cannot convert from int to shorts + = i;//+=the assignment operator has the display type conversion function, which is equivalent to s= (short) s=i; !!!System.out.println ("s=" +s);// the        intx = 0; inty = 0; intz = 0; Booleanb; A= (x>0) & (y++>1);//False&falseSystem.out.println ("a=" +a);//falseSystem.out.println ("y=" +y);//1b = (x>0) && (z++>1);//false first False then the second one does not operateSystem.out.println ("b=" +b);//falseSystem.out.println ("z=" +z);//so here's 0 instead of 1.A = (x>0) | (y++>1);//False|falseSystem.out.println ("a=" +a);//falseSystem.out.println ("y=" +y);//2b = (x>0) | | (z++) >1;//false| | False short-circuit operation, the first is true when the second one does not operateSystem.out.println ("b=" +b);//falseSystem.out.println ("z=" +z);//1

Java Basics-Operators (03)