How do I run a batch file from my Java Application

Question

In my Java application, I want to run a batch file that calls "scons -Q implicit-deps-changed build\file_load_type export\file_load_type"

It seems that I can't even get my batch file to execute. I'm out of ideas.

This is what I have in Java:

Runtime.
   getRuntime().
   exec("build.bat", null, new File("."));

Previously, I had a Python Sconscript file that I wanted to run but since that didn't work I decided I would call the script via a batch file but that method has not been successful as of yet.

Answer 1

Batch files are not an executable. They need an application to run them (i.e. cmd).

On UNIX, the script file has shebang (#!) at the start of a file to specify the program that executes it. Double-clicking in Windows is performed by Windows Explorer. CreateProcess does not know anything about that.

Runtime.
   getRuntime().
   exec("cmd /c start \"\" build.bat");

Note: With the start \"\" command, a separate command window will be opened with a blank title and any output from the batch file will be displayed there. It should also work with just `cmd /c build.bat", in which case the output can be read from the sub-process in Java if desired.

Answer 2

Runtime runtime = Runtime.getRuntime();
try {
    Process p1 = runtime.exec("cmd /c start D:\\temp\\a.bat");
    InputStream is = p1.getInputStream();
    int i = 0;
    while( (i = is.read() ) != -1) {
        System.out.print((char)i);
    }
} catch(IOException ioException) {
    System.out.println(ioException.getMessage() );
}

Answer 3

I had the same issue. However sometimes CMD failed to run my files. That's why i create a temp.bat on my desktop, next this temp.bat is going to run my file, and next the temp file is going to be deleted.

I know this is a bigger code, however worked for me in 100% when even Runtime.getRuntime().exec() failed.

// creating a string for the Userprofile (either C:\Admin or whatever)
String userprofile = System.getenv("USERPROFILE");

BufferedWriter writer = null;
        try {
            //create a temporary file
            File logFile = new File(userprofile+"\\Desktop\\temp.bat");   
            writer = new BufferedWriter(new FileWriter(logFile));

            // Here comes the lines for the batch file!
            // First line is @echo off
            // Next line is the directory of our file
            // Then we open our file in that directory and exit the cmd
            // To seperate each line, please use \r\n
            writer.write("cd %ProgramFiles(x86)%\\SOME_FOLDER \r\nstart xyz.bat \r\nexit");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                // Close the writer regardless of what happens...
                writer.close();
            } catch (Exception e) {
            }

        }

        // running our temp.bat file
        Runtime rt = Runtime.getRuntime();
        try {

            Process pr = rt.exec("cmd /c start \"\" \""+userprofile+"\\Desktop\\temp.bat" );
            pr.getOutputStream().close();
        } catch (IOException ex) {
            Logger.getLogger(MainFrame.class.getName()).log(Level.SEVERE, null, ex);

        }
        // deleting our temp file
        File databl = new File(userprofile+"\\Desktop\\temp.bat");
        databl.delete();

Answer 4

This code will execute two commands.bat that exist in the path C:/folders/folder.

Runtime.getRuntime().exec("cd C:/folders/folder & call commands.bat");

Answer 5

The executable used to run batch scripts is cmd.exe which uses the /c flag to specify the name of the batch file to run:

Runtime.getRuntime().exec(new String[]{"cmd.exe", "/c", "build.bat"});

Theoretically you should also be able to run Scons in this manner, though I haven't tested this:

Runtime.getRuntime().exec(new String[]{"scons", "-Q", "implicit-deps-changed", "build\file_load_type", "export\file_load_type"});

EDIT: Amara, you say that this isn't working. The error you listed is the error you'd get when running Java from a Cygwin terminal on a Windows box; is this what you're doing? The problem with that is that Windows and Cygwin have different paths, so the Windows version of Java won't find the scons executable on your Cygwin path. I can explain further if this turns out to be your problem.

Answer 6

To expand on @Isha's anwser you could just do the following to get the returned output (post-facto not in rea-ltime) of the script that was run:

try {
    Process process = Runtime.getRuntime().exec("cmd /c start D:\\temp\\a.bat");
    System.out.println(process.getText());
} catch(IOException e) {
    e.printStackTrace();
}