run setx command using java [duplicate]

Question

I am writing a java code that will append a path string to the %PATH% variable using java

In command prompt the command is

setx PATH "%PATH%;C:\my Path\"

In java here is my code:

import java.io.File;
import java.io.IOException;

public class AddToPATHVariable {
    public static void main(String[] args) throws InterruptedException, IOException {
        String folderPath = "C:\\my Path\\";
        System.out.println(folderPath);
        Runtime rt = Runtime.getRuntime() ;
        Process p = rt.exec("setx PATH \"%PATH%;" + folderPath + "\"");
        p.waitFor();
        p.destroy();
    }

}

The issue is that my command line prompt is append the new string perfectly. But java code is make the value to path variable to be %PATH%;C:\my Path\

someone please guide me in this regard.

Answer 1

Well, as nothing is in charge of converting %PATH% it simply is not converted !

More seriously, it is the cmd.exe interpretor that actually does the translation of environment variables and you do not use it. To have it to work, you must :

1. convert the environment variable PATH to its value in java code

   String path = System.getenv("PATH");
   

2. use the converted String in your command

   Process p = rt.exec("setx PATH \"" + path + ";" + folderPath + "\"");
   

EDIT :

To really be sure of what happens, you can display the generated command before executing it :

String cmd = "setx PATH \"" + path + ";" + folderPath + "\"";
Process p = rt.exec(cmd);