Question

I have a C#.Net console app code that transfers files between linux and windows ftp servers.

The code’s behavior is that I automatically open a console to display status of the file transfer. While transferring files to and from the windows server, I need to display an indicator that the file transfer is on-going (using symbols that look like they are moving or turning) . These symbols are as follows : “|” –> “/” –> “-” –> “\” –> “|”

There had been no problem displaying the said “indicator/symbols” in C#.Net using the following codes :

ProcessStartInfo PSI = new ProcessStartInfo("CMD.exe", "/C [here is the call to psftp / ftp scripts]"); 

String SymbolChar = "|";
Process proc = Process.Start(PSI); 

        while (true)
        {
            Thread.sleep(20);


            if (proc.HasExited)
            {
                Console.WriteLine("\b-> Done\n");
                break;
            }
            else
            {
                SymbolChar = NextChar(SymbolChar);
                Console.Write("\b{0}", SymbolChar);
            }
        }
        StreamReader srError = proc.StandardError;
        StreamReader srOutput = proc.StandardOutput;

//method used to animate status during process
    private static String NextChar(String sCurrentChar)
    {
        String sTempChar = "";

        if (sCurrentChar.equals("|")) {
            sTempChar = "/";
        }
        else if (sCurrentChar.equals("/")) {
            sTempChar = "-";
        }
        else if (sCurrentChar.equals("-")) {
            sTempChar = "\\";
        }
        else if (sCurrentChar.equals("-")) {
            sTempChar = "\\";
        }
        else if (sCurrentChar.equals("\\")) {
            sTempChar = "|";
        }

        return sTempChar;
    }

My problem started when I converted the said codes into java using the following :

String sParam = "bash " + [here is the call to psftp / ftp scripts];
String cmd[] = {"/bin/bash","-c",sParam};
Process proc = Runtime.getRuntime().exec(cmd);

Above code is perfectly working.
Problem is I don’t know how to display the “animated” characters anymore.
I suddenly don’t know (and I badly need help on) how to convert this :

Process proc = Process.Start(PSI); 

        while (true)
        {
            Thread.sleep(20);


            if (proc.HasExited)
            {
                Console.WriteLine("\b-> Done\n");
                break;
            }
            else
            {
                SymbolChar = NextChar(SymbolChar);
                Console.Write("\b{0}", SymbolChar);
            }
        }

Do you have any idea as to what I can use for the line “if (proc.HasExited)” in java so that I could move forward?

Sorry for the long explanation.
I really, really need help.

Thank you very much in advance!

Answer 1

You could use ‘Process.exitValue()’ and catch the Exception (it will throw an Exception if the process is not done yet). If the value is 0 the process exited normally. However this is rather ugly IMHO.

The only ‘proper’ way I know in Java to wait for a process to finish is to have the current Thread block until the Process is done with ‘Process.waitFor()’.

This would however require a different thread to display your progress animation since your current thread is blocked and waiting for the Process to finish.