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Today, I will talk to you about the basic grammar of Java, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following content for you. I hope you can get something according to this article.

A Java program can be thought of as a collection of objects that work together by calling each other's methods. The following briefly describes the concepts of classes, objects, methods, and instance variables.

Object: an object is an instance of a class that has state and behavior. For example, a dog is an object, its status is: color, name, breed; behavior: wagging tail, barking, eating and so on.

Class: a class is a template that describes the behavior and state of a class of objects.

Method: a method is a behavior, and a class can have many methods. Logical operations, data modifications, and all actions are done in the method.

Instance variables: each object has unique instance variables, and the state of the object is determined by the values of these instance variables.

Let's look at a simple Java program that prints the string HelloWorld

/ * *

* Created by IntelliJ IDEA.

*

* @ author: lida

* @ date: 2018-05-15

* @ time: 17:13:02

, /

Public class HelloWorld {

/ * the first Java program

* it will print the string HelloWorld

, /

Public static String HELLO_WORLD= "Hello World"

Public static void main (String [] args) {

System.out.println (HELLO_WORLD)

}

}

If you haven't installed IDE, you can put it in notepad by code and name it not HelloWorld.java, then open cmd, find the location of the file and use javac HelloWorld.java to compile, and then java HelloWorld.java to run it.

Let's take a look at what you need to pay attention to when writing code:

The first letter of the class name is capitalized, if the class name consists of several words, then the first letter of each word should be capitalized, for example, MyFirstJavaClass follows the hump form, with the exception of the following form: DO\ BO\ VO, etc.

The method name begins with a lowercase letter. If it is composed of multiple words and uniformly uses lowerCamelCase style, it must follow the hump form.

Constant names are all capitalized and words are separated by underscores

Java identifier:

All ① identifiers should start with the letter (Amurz or Amurz), the dollar sign ($), or the underscore (_).

The first character of ② can be followed by a combination of any character

The ③ keyword cannot be used as an identifier

④ identifiers are case sensitive

Java modifier

Like other languages, Java can use modifiers to modify methods and properties in a class. There are two main types of modifiers:

Access control modifiers: default, public, protected, private

Non-access control modifiers: final, abstract, strictfp

The difference between Java source program and compiled operation

Java comment

Java supports single-line comments and multiple-line comments

Multiple lines:

/ *

* this represents a multiline comment

* / public class HelloWorld {

/ * the first Java program

* it will print the string HelloWorld

, /

Public static String HELLO_WORLD= "Hello World"

Public static void main (String [] args) {

System.out.println (HELLO_WORLD)

}

}

Single line: / / this represents a single line comment

Public class HelloWorld {

/ / the first Java program

/ / it will print the string HelloWorld

Public static String HELLO_WORLD= "Hello World"

Public static void main (String [] args) {

System.out.println (HELLO_WORLD)

}

}

You can also express a single-line comment in this way

Public class HelloWorld {

/ * the first Java program, which prints the string HelloWorld*/

Public static String HELLO_WORLD= "Hello World"

Public static void main (String [] args) {

System.out.println (HELLO_WORLD)

}

}

Java blank line

Blank lines or annotated lines in Java code will be ignored when Java compiles. Do you have any further understanding of the basic syntax of Java? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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