Let's suppose you wrote a piece of Java code that needs some user input - and you used something like
String text = stdin.readLine();
Now you want to run or debug it inside JDeveloper, but how do you get JDeveloper to prompt you for the input value?
Here is the "secret trick":
Go into the project properties and edit the current Run/Debug Configuration.
Under the tools settings node you'll see that the last item allows you to specify "Allow Program Input"
check this box and run your project.
Now when you hit the input request look at your log window - just below it you'll see a little input field ready for your input: