execute file from defined directory with Runtime.getRuntime().exec

Question

I just want to execute my file from a specific folder. in my case /data/data/my-package/files/. So i tried :

 Process process2=Runtime.getRuntime().exec("cd /data/data/my-package/files/");
 process2.waitFor();
 process2=Runtime.getRuntime().exec("./myfile");

It doesn't work. could anyone tell me please the right way to do that . Thanks

Answer 1

It should be possible to call the executable with a specific working directory using Runtime.exec(String command, String[] envp, File dir)

as follows:

Process process2=Runtime.getRuntime().exec("/data/data/my-package/files/myfile",
        null, new File("/data/data/my-package/files"));

maybe without the full path to myfile

Process process2=Runtime.getRuntime().exec("myfile",
        null, new File("/data/data/my-package/files"));

Context#getFilesDir() instead of hardcoding the path should work too and is safer / cleaner than specifying the path yourself since it is not guaranteed that /data/data/.. is always the correct path for all devices.

Process process2=Runtime.getRuntime().exec("myfile",
        null, getFilesDir()));

The problem with cd somewhere is that the directory is changed for a different Process so the second call to exec in a new Process does not see the change.

Answer 2

It works for me when I use the following overloaded method:

public Process exec(String command, String[] envp, File dir)

For example:

File dir = new File("C:/Users/username/Desktop/Sample");
String cmd = "java -jar BatchSample.jar";
Process process = Runtime.getRuntime().exec(cmd, null, dir);

The command just stores the command you want to run in command line. dir just stores the path of your .jar file to be executed.