Strange behaviour surrounding clear screen and ConsoleReader.clearScreen()

[JDurston]

Linux x86-64; Ubuntu; Terminal; zsh

I noticed some strange behaviour when trying to clear the screen.
Attempts to clear the screen do not work with usual method of System.out.print("\u001b[2J").
Furthermore, when ConsoleReader.clearScreen is used, the screen WILL clear, BUT a double command prompt (--+--> --+-->) appears!

Example (swap con.clearScreen and System.out... to see both 'features'):

class TestJline {
    private static final String ERASE_DISPLAY = "\u001b[2J";
    public static void main (String argv[]) {
        try {
            ConsoleReader con = new ConsoleReader();
            con.setPrompt("--+--> ");

            System.out.print(ERASE_DISPLAY);
            System.out.println("Press any key to continue...");
            con.readCharacter();
            //con.clearScreen();
            System.out.print(ERASE_DISPLAY);

            System.out.println("Here is a prompt. Do something and press enter to continue...");
            String line = con.readLine();
            //con.clearScreen();
            System.out.print(ERASE_DISPLAY);

            System.out.println("You typed: ");
            System.out.println(line);
            System.out.println("Press any key to exit. ");
            con.readCharacter();
            //con.clearScreen();
            System.out.print(ERASE_DISPLAY);

            System.out.println("Thank You. Goodbye.");
            System.out.println("");
        } catch(IOException e) {
            //What to do in the event of an IOException:
            e.printStackTrace();
        } finally {
            try {
                TerminalFactory.get().restore();
            } catch(Exception e) {
                e.printStackTrace();
            }   
        }   
    }