Using Java ProcessBuilder to run native Windows .exe producing error :: The directory name is invalid

I have the following Java code to run a native Windows .exe file using ProcessBuilder

public class HMetis {
    private String exec_name = null;    
    private String[] hmetis_args = {"hmetis.exe", "null", "2", "1", "10", "1", "1", "1", "0", "0"};

    private Path path;
    private File file;

    public HMetis(String hgraph_exec, String hgraph_file) {
        this.exec_name = hgraph_exec;       
        this.hmetis_args[1] = hgraph_file;
    }       

    public void runHMetis() throws IOException {    
        this.path = Paths.get("C:\\hMetis\\1.5.3-win32");
        this.file = new File(path+"\\"+this.exec_name+".exe");      

        ProcessBuilder pb = new ProcessBuilder(this.hmetis_args);
        pb.directory(this.file);

        try {       
            Process process = pb.start();                       
        } finally {
            // do nothing
        }
    }
}

after running this code I am getting the below error although from the message it seems the directory name is fully formed and OK !! Any suggestions please?

Cannot run program "hmetis.exe" (in directory "C:\hMetis\1.5.3-win32\hmetis.exe"):CreateProcess error=267, The directory name is invalid

Solution

You are using the complete path to the executable file as the ProcessBuilder's working directory:

this.file = new File(path+"\\"+this.exec_name+".exe");      
ProcessBuilder pb = new ProcessBuilder(this.hmetis_args);
pb.directory(this.file);
                    ^
                    |
                    ++++++++ "C:\hMetis\1.5.3-win32\hmetis.exe"
                             should be "C:\hMetis\1.5.3-win32"

However, you want to set the working directory only, like

pb.directory(this.path.toFile());

In addition, it seems that ProcessBuilder.directory() does not set the "working directory" as one might expect - at least not to find the executable. A similar issue is described at ProcessBuilder can't find file?!. At least on Windows, executables in the current working directory are usually found first (Unix is a different thing).

An easy fix would be to add the absolute path name to the command array, like

String[] hmetis_args = {"C:\\hMetis\\1.5.3-win32\\hmetis.exe", "null", "2", "1", "10", "1", "1", "1", "0", "0"};