import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Executer {

    public static int execNull(String... cmd) throws IOException, InterruptedException {
        return exec(Runtime.getRuntime().exec(cmd),
                new NullStreamer(), new NullStreamer());
    }

    public static int execStd(String... cmd) throws IOException, InterruptedException {
        return exec(Runtime.getRuntime().exec(cmd),
                PrintStreamer.stdOutStreamer(), PrintStreamer.stdErrStreamer());
    }

    public static int exec(Process proc, ExecRunable stdout, ExecRunable stderr) throws InterruptedException {
        stdout.setStream(proc.getInputStream());
        stderr.setStream(proc.getErrorStream());
        Thread stdoutThread = new Thread(stdout);
        Thread stderrThread = new Thread(stderr);
        stdoutThread.start();
        stderrThread.start();
        return proc.waitFor();
    }

    public static interface ExecRunable extends Runnable {

        public void setStream(InputStream stream);
    }

    public static abstract class Streamer implements ExecRunable {

        protected InputStream input;

        @Override
        public void setStream(InputStream stream) {
            this.input = stream;
        }
    }

    public static class NullStreamer extends Streamer {

        @Override
        public void run() {
            try {
                int count;
                while ((count = input.available()) > 0) {
                    input.skip(count);
                }
            } catch (IOException ex) {
                Logger.getLogger(Executer.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    public static class PrintStreamer extends Streamer {

        private PrintStream outStream;
        private String name;

        public PrintStreamer(PrintStream outStream, String name) {
            this.outStream = outStream;
            this.name = name;
        }

        public String getName() {
            return name;
        }                

        public static PrintStreamer stdOutStreamer() {
            return new PrintStreamer(System.out, "stdout");
        }

        public static PrintStreamer stdErrStreamer() {
            return new PrintStreamer(System.err, "stderr");
        }

        @Override
        public void run() {
            try {
                InputStreamReader reader = new InputStreamReader(input);
                char[] buffer = new char[256];
                int count;
                while ((count = reader.read(buffer)) > 0) {
                    outStream.print(new String(buffer, 0, count));
                }
            } catch (IOException ex) {
                Logger.getLogger(Executer.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}