Java Basic Syntax

Before starting the Java basic syntax, explain the basic specifications of the Java program:

• Case sensitive, such as person and person are different
• The first letter of the class name is capitalized, and if the class name consists of multiple words, the first letter of each word is capitalized, for example HelloWorld
• Method names should follow the hump naming method, beginning with a lowercase letter, if it contains multiple single, followed by a single capitalization, such as Findminnumber
• The source file name must be the same as the class name
• Java program starts execution by public static void main (string [] args) method

Java identifiers, such as class name, variable name, method name

• All representations are (A-Z) or (A-Z) or ($) or (_) Start
• The first character is followed by a (A-Z) or (A-Z) or ($) or (_) or (any number) combination
• Keyword cannot be used as an identifier
• Identifier Case sensitive
• Examples of legal identifiers: Age, $salary, _value
• Examples of illegal identifiers: 2twice,-salary

Java modifiers, modifying methods and properties in a class

• Access control modifier: default,public,protected,private
• Non-access control modifier: FINAL,ABSTRACT,STRICTFP

Java variables

• class variables
• Member variables
• Local variables

Java arrays

An array of objects on the heap that can hold multiple variables of the same type, named Specification byte[] Buffer

Java Enumeration

Enumerations can only be pre-set values.

class HelloWorld {    public static void main(String[] args) {        FreshJuice juice = new FreshJuice();        juice.size = FreshJuice.FreshJuiceSize.MEDIUM;    }}class FreshJuice {    enum FreshJuiceSize { SMALL, MEDIUM, LARGE }    FreshJuiceSize size;}

Java keywords, keywords are lowercase access control

• Private
• Protected
• Public

Class, method, and variable modifiers

• Abstract
• Class
• Extends
• Final
• Implements
• Interface
• Native
• New
• Static
• Strictfp
• Synchronized
• Transient
• Volatile

Program Control statements

• Break
• Continue
• Do
• While
• For
• If
• Else
• instanceof
• Return
• Switch
• Default
• Case

Error handling

• Assert
• Catch
• Finally
• Throw
• Throws
• Try

Package related

• Import
• Package

Basic type

• Boolean
• Byte
• Char
• Double
• Float
• Int
• Long
• Short
• Null

Variable reference

• Super
• This
• void

Reserved keywords

• Goto
• Const

Java Basic Syntax