The most comprehensive JDK installation tutorial: JDK download and install tutorial + CMD Java entry is effective but Javac entry is invalid Solution

java ， jdk (Java Development Kit Java) ， java jdk ： （[ ： ：] https://editor.csdn.net/md/?articleid=113858056))))))))))))))))))))))))))
1. JDK download address:
http://www.oracle.com/technetwork/java/javase/downloads/index.html

You should see the interface shown in the figure below:

2. Click on the place mentioned by the arrows in the above figure, and the following interface will appear. Currently, you need to select the appropriate version according to your computer system. Pre-select version and download as follows:

3. To install the JDK twice later (remember to change the installation path according to the second picture, and don’t install everything on the system drive…):
(1) Double-click the installation interface, as shown below:





4. After the installation is completed, you need to set the environment variable. Right click on My Computer Theme – Advanced System Settings you will see the interface as follows:

5. Click on the environment variable in the above image, and then run the environment variable configuration:
(1) Click the new button under the system variable, variable name java_home (representing the JDK installation path), the value corresponds to the JDK installation path.

(2) Continue to create a new Path class variable in the system variable, and its variable value is shown in the figure below:

Note here: There is a small dot in front. Entity Entity Entity Many beginners fall into this hole with their own set of environment variables.
(3) Find the path variable in your system variables. You need to add additional code to your value field:

%JAVA_HOME%\bin;%JAVA_HOME%\jre\bin;

  
  

Currently, you have to add it behind your original value range. Don’t forget to add the English language account behind the original domain.
Finally, click OK, the JDK environment variable configuration is now complete.
6. Check if the environment variable you are setting is correct,
(1) Windows + R, type CMD and enter the command line interface as shown below:

(2) Enter the command java -version. It may appear as shown below. You can see which JDK version you have installed.

(3) Enter a Javac command to display the following prompts:

(4) Enter the Java command to appear as shown in the figure below

7. Write a piece of code to test it
(1) I have created a folder called Javafile on drive E. It contains a Java file called Testjava.java. For now you have to pay attention.
(2) You need to write the following code in your file:

public class TestJava{
public static void main(String[] args){
	System.out.println("I am a  java new learner!");
}