Non-professional Code farmer Java Learning Note 2 Java language basics

Java Language Basics

(i) Procedural composition

Slightly

(ii) Data type variables and constants

1. Data type (similar to C #)

boolean bool 8 bit

BYTE 8-128-127

Character Char 16

Short-integer 16

Int 32

Long 64

Float 32

Double 64

2. Identifier-Variable constant method object and class name tag

Alphanumeric also has two special symbols _ and $

Letter underline or dollar sign start

3. Constants

4. Variables

(c) Expressions

1. Assignment and coercion type conversions

Tostring () weak conversion

Type = (type) variable: The value of a= (int) B;a is forcibly converted to int\ b

2. String connection

General is the + number, indicating the connection, as well as + = This column of the combination of symbols, etc.

3. Arithmetic Operation +-*/

4. Relational operations: = = = = = < > etc.

5. Logical operation, relatively complex

& with | or! Take the reverse; | | This type of coincident, right-hand expression may not be executed

6. Bitwise OPERATION: binary unit position >>,<< ~ (binary inverse value),>>> right shift not enough to fill 0

7. When other:b>a?a:b; are mixed, use () can be performed preferentially

8. Priority of operation: strong-Weak

.  [] () ~!++--*/+->> <>=! = &|  &&| | ?: = (assigned value)

9. Notes

//  /**/

(iv) Process Control statements

1. Branch statements

If (A>B)

A

Else

B

Swith (variable, expression)/* differs from C # in case not break;*/

Case value, operation result: statement 1; .... ; default: statement;

2. Looping statements

while (n<10000)

{Executed statement;}

Do

{Executed statement;}

while{conditions of cessation;}

3. Jump statements

Continue:

First-loop:

Execute the statement;

If (condition)

{Continue first-loop;}

Break statement: Only valid if you want to put it in a loop statement

Return statement: Returns, can be followed with parameters, programs, etc., without representing no return value, terminating execution

Non-professional Code farmer Java Learning Note 2 Java language basics