Windows environment variables cannot be parsed correctly

Question

Using a command such as "echo %CLASSPATH%" in the cmd window returns ".;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.;" instead of ".;C:\Program Files\Java\jdk-17.0.5\lib\dt.jar;C:\Program Files\Java\jdk-17.0.5\lib\tools.jar;"

However, if you use the command "echo %JAVA_HOME%", it returns "C:\Program Files\Java\jdk-17"

Some of these environment variables can be parsed, while in some situations they cannot be parsed, which bothers me, hoping to receive a suitable solution.

Version:

Windows11 professional workstation 23H2

22635.2700

Windows Feature Experience Pack 1000.22678.1000.0

Answer 1

I understand your frustration. It seems that you are facing a common problem with Windows environment variables that are not parsed correctly in some situations. There are a few possible reasons and solutions for this issue:

• One reason is that the environment variables are read from the registry in alphabetic order, and if you have a variable that depends on another variable that is alphabetically greater, the first variable will not be expanded. For example, if you have CLASSPATH depending on JAVA_HOME, and both are REG_EXPAND_SZ type, CLASSPATH will not be expanded because C < J. A solution for this is to change the order of the variables or use REG_SZ type for JAVA_HOME¹.
• Another reason is that the environment variables are not refreshed in the current command prompt, but only in subsequent ones. This means that if you change a variable using setx.exe, you will not see the effect in the same command prompt, but only in a new one. A solution for this is to use refreshenv command to refresh the environment variables without restarting the command prompt².
• A third reason is that there are white spaces in the environment variables that cause parsing errors. For example, if you have a space at the end of JAVA_HOME, it will not be recognized correctly. A solution for this is to remove any white spaces in the environment variables³.