How to get 2nd app to write to 1st app "System.In"?

Question

Hey, I am trying to build a program that will control another program. It will do this by reading the output of the program and then sending it information as if a user had typed it in.
The problem is that the 2nd app (referred from here on as the "CONTROLLER"), when run, hangs on the spot where the 1st app (referred from here on as the "HOST"), is waiting for "System.in" input.
So the CONTROLLER will read the first line, display it, but then where it is supposed to wait for the user to type something in and write it to the HOST (which is using System.in for input), it hangs up. Because I have the .close() method inside my methods, it now at least closes the app instead of freezing.
I've read http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html "When Runtime.exec() won't", and it doesn't really address my problem except to say "Thus, to circumvent the second pitfall -- hanging forever in Runtime.exec() -- if the program you launch produces output or expects input, ensure that you process the input and output streams."
Which is fine, but I don't know how to handle the HOST using System.in waiting for input in my CONTROLLER app. Anyone got a method I can use for this? Here is the code.
HOST:
import java.io.*;
public class myTest4 {
     public myTest4() {
          InputStreamReader inText = new InputStreamReader(System.in);
          BufferedReader buffText = new BufferedReader(inText);
          try {
               System.out.print("Enter Customer Number:  ");
               String firstIn = buffText.readLine();
               int newvalue = Integer.parseInt(firstIn);
               char char1 = firstIn.charAt(0);
               System.out.println("Customer number entered: " + firstIn);
                    if (char1 == '1') {
                         System.out.print("Enter Comment:  ");
                         String comment = buffText.readLine();
                         System.out.println("You entered - " + comment);
                         System.out.println("Press ENTER to exit:");
                         System.in.read(new byte[10]);
                         System.exit(0);
                    else {
                         System.out.println("Press ENTER to exit:");
                         System.in.read(new byte[10]);
                         System.exit(0);
          catch(IOException err) {
              System.out.println("Error reading line");
          catch(NumberFormatException err) {
               System.out.println("Error Converting Number");
     public static void main(String[] args) {
               myTest4 free = new myTest4();
     }CONTROLLER:
import java.io.*;
class LegacyProviderTest {
     protected Process theProcess;
     public void startSession(String command)
          throws IOException, SecurityException, NullPointerException,
          IllegalArgumentException, InterruptedException
          theProcess = Runtime.getRuntime().exec(command);
     public String readLines()
     throws IOException
          char[] theLine = new char[5000];
          int index = 0;
          BufferedReader is = new BufferedReader(new InputStreamReader(theProcess.getInputStream()));
          while (index < theLine.length)     {
               int theCharacter = is.read();
               if (Character.isISOControl((char)theCharacter)) {
                    break;
               else {
                    theLine[index++] = (char)theCharacter;
          is.close();
          String theResult = new String(theLine);
          return theResult;
     public void writeLines(String line)
     throws IOException
          char[] theChars = new char[line.length()];
          BufferedWriter os = new BufferedWriter(new OutputStreamWriter(theProcess.getOutputStream()));
          for (int i=0; i < line.length(); i++) {
               theChars[i] = line.charAt(i);
          os.write(theChars);
          os.close();
     public static void main(String args[]) {
          String input;
          LegacyProviderTest legacy = new LegacyProviderTest();
          try {
               legacy.startSession("java mostSimple");
               input = legacy.readLines();
               System.out.println("Read input: " + input);
               if (!input.equals("Enter Customer Number:  ")) {
                    System.out.println("Invalid response: " + input);
                    System.exit(1);
               legacy.writeLines("12345");
               input = legacy.readLines();
               System.out.println("Read input: " + input);
               if (!input.equals("Enter comment:  ")) {
                    System.out.println("Invalid response: " + input);
                    System.exit(1);
               legacy.writeLines("hi there");
               legacy.writeLines("");
               System.out.println("Yahoo!!");
          catch (Exception e)     {
               System.out.println("Got exception " + e);
               System.exit(1);

Answer 1

>
Process p = Runtime.getRuntime().exec(my_cmd);
InputStream inputStream = p.getInputStream();
If you notice, I have the InputStream already initialized and then buffered, and the process is initializing correctly (to the point where it asks for System.in input).