Java language portal - the first HelloWorld program

1. official website to download Jdk

　　Here is the official website to download URL: https://www.oracle.com/technetwork/java/javase/downloads .

　　1.1 After opening the following screen appears:

Select the corresponding version 1.2: Pick Jdk8 version.

The latest is not necessarily the best, stability is king.

2. Install

2.1 Double-click the installation package opens, click Next.

2.2 Click Change route path, and then click Next.

2.3 Click OK

2.4 installation is complete, closed

3. Right-click My Computer environment configuration -> Properties -> Advanced System Settings.

A total of three steps environment configuration

3.1 JAVA_HOME: JDK installation directory configuration

The top is a user variable, below is a system variable, said here about the difference between them: a user variable only for the current computer user, the system variables for all users.

Here to system variables, for example.

Find JAVA_HOME variable, not the new.

3.2 Configuration PATH: Configure JDK installation bin (command) directory

Find the PATH variable, double-click New to enter

3.3 Configuring the CLASSPATH variable:

" . Means the current directory" (.class files directory: directory java file)

Here, the entire jdk installation configuration is over.

If unsure, you can test:

Open window + R -> Input cmd -> Open command line input java

Enter javac

Enter java -version (java behind spaces) see the version number

4. The first program HelloWorld

4.1 Create a text file named HelloWorld.java .java ending in the D drive

Double-click to open the file, enter the following

public class HelloWorld{
    public static void main(String[] args){
         System.out.println("Hello World");
    }

CTRL+s保存

4.2在当前文件所在目录下输入cmd，进入命令行

输入命令：编译：javac HelloWorld.java

　　　　　运行：java HelloWorld

到这里第一个HelloWorld程序开发就结束了

第一次写博客还请大家提出宝贵意见

Java language portal - the first HelloWorld program

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