Here are the details:

1.JAVA_HOME

JAVA_HOME points to the path where the JDK is installed

You should be able to find directories such as bin, lib, and so on, under that path

For example, my setup would have been JAVA_HOME=C:\j2sdk1.4.2_09;

2. PATH

The purpose of setting PATH is to point to the JDK's bin directory

In the bin directory are the various compilation and execution commands

For example, my setup would be PATH=C:\j2sdk1.4.2_09\bin;

My setup would be PATH=C:\j2sdk1.4.2_09\bin;

If I were to set it to PATH=C:\j2sdk1.4.2_09\bin;

It should be noted that the system itself has a PATH environment variable, as long as the C:\j2sdk1.4.2_09\bin;C:\j2sdk1.4.2_09\jre\bin; directly behind the can be used to put the middle of the use of ";" separation

3.

3. CLASSPATH

CLASSPATH set the path of the class, but also the most important

such as my settings should be CLASSPATH=. ;C:\j2sdk1.4.2_09\lib;C:\j2sdk1.4.2_09\lib\tools.jar;

Placing the "." and ";" at the top, meaning look in the current directory first

The above configurations are all done under the premise that my JDK installation directory is C:\j2sdk1.4.2_09

You can modify it accordingly based on the actual installation directory

Configuration method:

Right-click on "My Computer" - -> -> lib\tools.jar;"

This is the first time that the JDK is installed in the current directory.

Click the "Environment Variables" button to bring up the "Environment Variables" panel, and configure the user variables or system variables accordingly

Note: The user variables are only valid for the user who is currently logged in to the machine, while the system variables are valid for all users who are logged in to the machine. You can configure them according to your own preferences in the corresponding variable environment

After all the environment variables have been configured, execute the java or javac commands directly in the command window, and the corresponding message will appear, indicating that the configuration has been successful

This is the first time that a java or javac command has been configured.