I'm making a C Assessment Program through Java, which has a bunch of programming questions for C, and it lets the user input an answer in the form of C code, and then press a "Compile" button, which is linked to a bat file that runs the user input code through gcc.

I've got the input and compiling working, but I need to get the output from the compiler and get that to print textarea within the program. I can get a simple "Hello, world" compiling, but I'm having trouble getting programs that require a user input with scanf, for example, to be printed.

else if(e.getSource().equals(compile)){



 if(questionNumber<1){
    JOptionPane.showMessageDialog(programFrame, "Please start the assessment", "Compile Error", JOptionPane.ERROR_MESSAGE);
   }
   else{
    FileOutputStream fileWrite;
    try {
     fileWrite = new FileOutputStream("demo/demo.c");
     new PrintStream(fileWrite).println(input.getText());//saves what the user has entered in to a C source file
     fileWrite.close();
     @SuppressWarnings("unused")
     Process process = Runtime.getRuntime().exec("cmd /c compile.bat");//runs the batch file to compile the source file
     compileCode();
     try{
      fileStream = new FileInputStream("demo/output.txt");
      inputStream = new DataInputStream(fileStream);
      bufferRead = new BufferedReader(new InputStreamReader(inputStream));

      while((stringLine = bufferRead.readLine())!=null){
       compiled.append(stringLine);
       compiled.append("\n");
      }
      inputStream.close();


     }
     catch(IOException exc){
      System.err.println("Unable to read file");
      System.exit(-1);
     }


    } 
    catch (IOException exc) {
     JOptionPane.showMessageDialog(programFrame, "Demo file not found", "File Error", JOptionPane.ERROR_MESSAGE);

    }
   }

This is the actionPerformed method for the "Compile" button, the compileCode() is the JFrame that displays the output and "compiled" is the textArea for the output.

My batch file is:

C:
cd dev-cpp\bin
gcc.exe H:\workspace\QuestionProgram\demo\demo.c -o demo > H:\workspace\QuestionProgram\demo\compilestatus.txt
demo > H:\workspace\QuestionProgram\demo\output.txt

I'm not sure how I can do it, so the frame is created for the output of the code if the code requires a user input as the command prompt doesn't open without adding "START" to .exec(), but then the frame appears before the program has finished running.

Also, how would I get the output of the compiler if the compile fails because of an error? The way I've got it in my batch file at the moment doesn't put anything in a text file if it fails.