Java Basic Syntax--(for future review)

1. Key words

Concept: Words that are given special meaning by Java.

Example: Declaring a class keyword: class

Access Rights keyword: public

static modifier keyword: static

No return value type keyword: void

2. Identifiers

Concept: A name used to standardize a custom in a program

Composition: Alphanumeric underscore $

Spec: Cannot start with a number

Cannot contain spaces

Characters other than $ cannot appear

Cannot use keywords

Note: Identifiers in Java are strictly case-sensitive

Recommendation: Custom name best to be known

3. Data storage format

The data is stored in the computer in the form of a binary complement.

Positive numbers: The original code, the inverse code and the complement are consistent.

Negative Number: The original code: positive source code based on the highest position is 1.

Anti-code: negative source of the highest bit remains unchanged, the number of the remaining bits is reversed.

Complement: Negative inverse code +1.

Extension: Octal starts with 0

Hex 0x Start

Conversion between the binary:

Decimal to N binary: integer part: Divide by N, remainder inverse

Fractional part: Times n Rounding, Integer rounding

N-Decimal: Weighted Expansion summation method

4. Data operation

The highest level in binary is the sign bit

Smallest unit in computer: bit shorthand b

Minimum unit of processing data in a computer: shorthand byte b

5. Data type (Java is a strongly typed programming language)

Basic data types

Integer type

byte short int Long is the number of bytes: 1 2 4 8

Floating point Type

The number of bytes for a float double is: 4 8

Character type

The number of bytes that char occupies is: 2

Boolean type

The number of bytes in a Boolean is: 1

Reference data type

Interface type

Array type

Class type

6. Variables

Concept: A container for data that can change

Declaration format: Variable type variable name = data;

Suggested naming method: Small Hump name method: MaxValue

7. Data type Conversion

Small type turn large type: automatic type conversion

Large type turn small type: forced type conversion

8. Operators

Arithmetic operators

+ - * / % ++ --

Assignment operators

= += -= *= /= %=

logical operators

Logic and (&& or &)

Logic or (| | or |)

Logical XOR (^)

Logical NON (!)

Comparison operators

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

Bitwise operators

Ternary operators

Escape character

9. How to compare the equality of string sequences: A.equals (b);

Compare the size of the string: A.compareto (b);

10, instanceof is a keyword and not a method, similar to the > number and the like.

Java Basic Syntax--(for future review)