Runtime.exec doesn't do anything… (no errors)

Question

I am trying to use java to run a batch file at an absolute location. The batch file will compile a couple of java files.

Here is the code which I have been trying:

String s=file.getAbsolutePath() + "\\compile.bat";
Runtime rut = Runtime.getRuntime();
try {
    rut.exec(new String[] {file.getAbsolutePath() + "\\compile.bat"});
}catch(IOException e1) {
    e1.printStackTrace();
}
System.out.println(s);

Now, when this code gets executed, I get no console errors, but the batch file is not run. When I run the batch file through Windows Explorer, however, the batch file works, compiles the files and closes when done.

Answer 1

How do you know that there were no console errors?

Try this:

String s=file.getAbsolutePath() + "\\compile.bat";
Runtime rut = Runtime.getRuntime();
try {
    Process process = rut.exec(new String[] {file.getAbsolutePath() + "\\compile.bat"});
    // prints out any message that are usually displayed in the console
    Scanner scanner = new Scanner(process.getInputStream());
    while (scanner.hasNext()) {
        System.out.println(scanner.nextLine());
    }
}catch(IOException e1) {
    e1.printStackTrace();
}
System.out.println(s);

Answer 2

Check the return value of the subprocess using exitValue() . Also read the error stream getErrorStream() if the exist value is non zero.

Answer 3

Note that when using your invocation of Runtime.exec , the working directory of the command being executed will be the current working directory of the java process. Does your batch file need to run in a specific directory?

If you need to set a specific working directory for the sub-process, you'll need to use another version of Runtime.exec .