import java.io.PrintStream;

/**
 *
 */
public class PythonInteractive {

    public static void main(String[] args) throws Exception {
        ProcessBuilder builder = new ProcessBuilder("python", "-i");
        builder.redirectErrorStream(true);
        Process p = builder.start();

        PrintStream printStream = new PrintStream(p.getOutputStream(), true);
        new Thread(() -> {
            int r;
            try {
                while (p.isAlive()) {

                    while (p.getInputStream().available() > 0) {
                        r = p.getInputStream().read();
                        System.out.print(Character.toString((char) r));
                    }
                    Thread.sleep(10);
                }
            } catch (Exception ex) {
                System.err.println(ex);
            }
        }).start();

        Thread.sleep(200);
        String cmd = "print (1+2)";
        System.out.println(cmd);
        printStream.println(cmd);
        Thread.sleep(200);
        p.destroy();

    }
}