Java Runtime.getRuntime（）。exec（）将不会执行python.exe

Question

For a project I need to start python.exe via Runtime.getRuntime.exec(). However, when I try to run it it won't execute, but it doesn't throw up an IOException. Here's the code:

try 
    {

        Process process=Runtime.getRuntime().exec("C:\\Program Files (x86)\\PythonTest\\python.exe");
    } 
    catch (IOException e) 
    {
        System.out.println("Cannot find python.exe");
        e.printStackTrace();
    }    

Answer 1

You need to get the output from the process and ( waitFor() it to finish). Something like,

final String cmd = "C:/Program Files (x86)/PythonTest/python.exe";
Process p = Runtime.getRuntime().exec(cmd);
final InputStream is = p.getInputStream();
Thread t = new Thread(new Runnable() {
  public void run() {
    InputStreamReader isr = new InputStreamReader(is);
    int ch;
    try {
      while ((ch = isr.read()) != -1) {
        System.out.print((char) ch);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
});
t.start();
p.waitFor();
t.join();

To actually do something with python you'll want to get the OutputStream .

Answer 2

I think that the problem is due to eval incorrectly splitting the command string. My understanding is that exec("C:\\\\Program Files (x86)\\\\PythonTest\\\\python.exe") will attempt to run an application called "C:\\\\Program" , passing it 2 command line arguments.

Try this instead:

 exec(new String[]{"C:\\Program Files (x86)\\PythonTest\\python.exe"});

The exec(String, ...) command line parsing is primitive, and often has the incorrect behaviour from the programmer's perspective. The best bet is often to split the command and arguments yourself.