Java: Smooth Keyboard Input?

public class Player implements KeyListener {    public static final int SPEED = 3;    private int vX, // velocity x                vY, // vel y                x,  // pos x                y;  // pos y    private boolean up,                    down,                    left,                    right;/* This is the only method that the client should ever call!   Instead of moving a sprite when you press a button,   you should be moving a sprite while certain states   hold. Also, do not animate the sprite in the event   handler! Animate it in your main rendering loop!!   That means that your main rendering loop will call   player.go() and nothing more. This will result in   smooth animation. If you rely on animating the sprite   in the keypressed method, the sprite will only move   when an event is fired. That's ugly!! */public void go() {    x += vX;    y += vY;    // etc...}private void update() {    vX = 0;    vY = 0;    if(down) vY = SPEED;    if(up) vY = -SPEED;    if(left) vX = -SPEED;    if(right) vX = SPEED;}public void keyPressed(KeyEvent e) {    switch(e.getKeyCode()) {        case KeyEvent.VK_DOWN: down = true; break;        case KeyEvent.VK_UP: up = true; break;        case KeyEvent.VK_LEFT: left = true; break;        case KeyEvent.VK_RIGHT: right = true; break;    }    update();}    public void keyReleased(KeyEvent e) {	switch(e.getKeyCode()) {	    case KeyEvent.VK_DOWN: down = false; break;	    case KeyEvent.VK_UP: up = false; break;	    case KeyEvent.VK_LEFT: left = false; break;	    case KeyEvent.VK_RIGHT: right = false; break;	}	update();    }}