Runtime.getRuntime().exec(cmd) hanging

Question

I am executing a command which returns me the Revision number of a file; \'fileName\'. But if there is some problem executing the command, then the application hangs up. Wha

Answer 1

This code is based on the same idea Arham's answer, but is implemented using a java 8 parallel stream, which makes it a little more concise.

public static String getOutputFromProgram(String program) throws IOException {
    Process proc = Runtime.getRuntime().exec(program);
    return Stream.of(proc.getErrorStream(), proc.getInputStream()).parallel().map((InputStream isForOutput) -> {
        StringBuilder output = new StringBuilder();
        try (BufferedReader br = new BufferedReader(new InputStreamReader(isForOutput))) {
            String line;
            while ((line = br.readLine()) != null) {
                output.append(line);
                output.append("\n");
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return output;
    }).collect(Collectors.joining());
}

You can call the method like this

getOutputFromProgram("cmd /C si viewhistory --fields=revision --project="+fileName);

Note that this method will hang if the program you are calling hangs, which will happen if it requires input.