NULL in previously set environment variable - batch-file

Question

I'm trying to make a basic Java IDE in Notepad++, which is easy as long as you don't use packages. But if you need to use the -classpath parameter, everything gets difficult.
I want to use these codes, I think you can get the idea:
NPP EXEC code:
NPP_SAVE
SET_ENV NPP_FULL_CURRENT_PATH=$(FULL_CURRENT_PATH)
SET_ENV NPP_CURRENT_DIRECTORY=$(CURRENT_DIRECTORY)
SET_ENV NPP_NAME_PART=$(NAME_PART)
npp_run cmd /k d:\Users\User\Desktop\script.cmd
script.cmd
SETX CLASSPATH %CD%
set /p deep=Deepness:
:START
if /I %deep% EQU 0 goto END
cd ..
set /a deep=deep-1
goto START
:END
SETX CLASSPATH %CD%
javac -g -cp %CLASSPATH% %NPP_FULL_CURRENT_PATH%
set /p input=Package:
SETX PACKAGE %input%
java -cp %CLASSPATH% %PACKAGE%.%NPP_NAME_PART%
cmd windows
D:\Users\User\Desktop\programozas\java\P05\konyves>SETX CLASSPATH D:\Users\User\Desktop\programozas\java\P05\konyves
SIKERÜLT: A megadott értéket sikerült menteni.
D:\Users\User\Desktop\programozas\java\P05\konyves>set /p deep=Deepness:
Deepness:1
D:\Users\User\Desktop\programozas\java\P05\konyves>if /I 1 EQU 0 goto END
D:\Users\User\Desktop\programozas\java\P05\konyves>cd ..
D:\Users\User\Desktop\programozas\java\P05>set /a deep=deep-1
D:\Users\User\Desktop\programozas\java\P05>goto START
D:\Users\User\Desktop\programozas\java\P05>if /I 0 EQU 0 goto END
D:\Users\User\Desktop\programozas\java\P05>SETX CLASSPATH D:\Users\User\Desktop\programozas\java\P05
SIKERÜLT: A megadott értéket sikerült menteni.
D:\Users\User\Desktop\programozas\java\P05>javac -g -cp NULL D:\Users\User\Desktop\programozas\java\P05\konyves\KonyvProba.java
(SIKERÜLT means SUCCESS, it managed to save the value)
THE PROBLEM
You can see the problem in the last line of the cmd window. -cp NULL
I don't understand why it's NULL, I've set it in the previous line.

Answer 1

These codes seem to work now, but may be unstable:
set CLASSPATH=%CD%
REM Type in the relative path deepness, for
REM example "package xxx.xxx.xxx;" means 3 deepness
REM No package means 0 deepness
set /p deep=Deepness:
set /a DEEP_FINAL=deep
:START
if /I %deep% EQU 0 goto END
cd ..
set /a deep=deep-1
goto START
:END
set CLASSPATH=%CD%
REM Compiling
javac -g -cp %CLASSPATH% %NPP_FULL_CURRENT_PATH%
REM Executing
if /I %DEEP_FINAL% EQU 0 goto NOPATH
REM May include a "cls" here
REM Type in the package name, for example
REM "package java.util;" becomes "java.util"
set /p PACKAGE=Package:
cls
java -cp %CLASSPATH% %PACKAGE%.%NPP_NAME_PART%
goto FINISH
:NOPATH
cls
java -cp %CLASSPATH% %NPP_NAME_PART%
:FINISH
NPPEXEC code:
cd d:
cd $(CURRENT_DIRECTORY)
NPP_SAVE
SET_ENV NPP_FULL_CURRENT_PATH=$(FULL_CURRENT_PATH)
SET_ENV NPP_CURRENT_DIRECTORY=$(CURRENT_DIRECTORY)
SET_ENV NPP_NAME_PART=$(NAME_PART)
npp_run cmd /k d:\Users\User\Desktop\script.cmd
This may be different for you. For example most users use the c: partition for the source files. Very important: you have to run Notepad++ as administrator! I'll test this from now on, and if it keeps working, I'll post it with more relevant tags, since it would be a Java IDE with Notepad++.

Answer 2

SETX does not set the environment variable in the current cmd instance, but for furure cmd instances. You need to execute a set command to set the value in the current instance.