How can I unblock from a Java started process?

Question

When executing some command(let\'s say \'x\') from cmd line, I get the following message: \"....Press any key to continue . . .\". So it waits for user input to unblock.

Answer 1

Use a PrintWriter to simulate some input:

        Process p = Runtime.getRuntime().exec(cmd, null, cmdDir);
        //consume the proces's input stream
        ........
        // deblock
        OutputStream outputStream = p.getOutputStream();
        PrintWriter pw = new PrintWriter(outputStream);
        pw.write("ok");
        pw.flush();
        int errCode = p.waitFor();

Answer 2

I think the recommended ray of executing external applications in Java is using a ProcessBuilder. The code looks like

//Launch the program
ArrayList<String> command = new ArrayList<String>();
command.add(_program);
command.add(param1);
...
command.add(param1);

ProcessBuilder builder = new ProcessBuilder(command);
//Redirect error stream to output stream
builder.redirectErrorStream(true);

Process process = null;
BufferedReader br = null;
try{
    process = builder.start();

    InputStream is = process.getInputStream();
    br = new BufferedReader( new InputStreamReader(is));
    String line;

    while ((line = br.readLine()) != null) {
         log.add(line);
    }
}catch (IOException e){
    e.printStackTrace();
}finally{
    try{
        br.close();
    }catch (IOException e){
        e.printStackTrace();
    }
}

The process object has a get[Input/Output/Error]Stream that could be used to interact with the program.