Kbhit em java

String letra="A"; //inicialmente A
while (true){
    System.out.println(letra); 
    while (não houver interrupção do teclado)
        letra=pegaLetraDigitadaNoTeclado();
    }
}

package teste;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JFrame;

public class Kbhit extends JFrame implements KeyListener {

	private static final long serialVersionUID = 1L;

	boolean kbhit = false;

	public static void main(String[] args) throws Exception {
		Kbhit kbhit = new Kbhit();
		while (!kbhit.kbhit()) {
			System.out.print(".");
			Thread.sleep(500);
		}
		kbhit.dispose();
	}

	public Kbhit() {
		setSize(320, 240);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		addKeyListener(this);
		setVisible(true);
	}

	public boolean kbhit() {
		return kbhit;
	}

	public void keyPressed(KeyEvent e) {
		kbhit = true;
		System.out.println("keyPressed");
	}

	public void keyReleased(KeyEvent e) {
		System.out.println("keyReleased");
	}

	public void keyTyped(KeyEvent e) {
		System.out.println("keyTyped");
	}

}