How to send keystroke/text to some another application/process

Hi,
does anybody know how to send keystroke or text to another application? The "another" application is not java application but it is for example notepad.
For example if I create two processes:

Process proc1 = Runtime.getRuntime().exec("notepad");
Process proc2 = Runtime.getRuntime().exec("notepad");

And I would like to send some text to some of this processes.
I have tried to use class Robot:

Robot robot = new Robot();
robot.keyPress(KeyEvent.VK_A);

The problem is, that this class sends the keystroke only to that window which is on top. I need to choose the particular process which the keystroke or some text receive.

Thanks in advance;)

For Windows when I want to do this, I use AutoIt, not Java.

Thank you for advice, I'll try this tool. However I have another question. Is it in java even possible to send keystroke to some specific application? Because I found similar topic on another forum, where somebody stated, that only way how to do this in java is via using some library in C++.

Agree. The way to do this in Java is to use the JNI library and link in a C or C++ program.

OK, Thank you.