The method clone() from the type Object is not visible

Question

Hi,
This is my 1st post here for a few years, i have just returned to java.
I am working through a java gaming book, and the "The method clone() from the type Object is not visible" appears, preventing the program from running. I understand "clone" as making a new copy of an object, allowing multiple different copies to be made.
The error occurs here
public Object clone() {
        // use reflection to create the correct subclass
        Constructor constructor = getClass().getConstructors()[0];
        try {
            return constructor.newInstance(new Object[] {
                (Animation)left.clone(),
                (Animation)right.clone(),
                (Animation)deadLeft.clone(),
                (Animation)deadRight.clone()
        catch (Exception ex) {
            // should never happen
            ex.printStackTrace();
            return null;
    }The whole code for this class is here
package tilegame.sprites;
import java.lang.reflect.Constructor;
import graphics.*;
    A Creature is a Sprite that is affected by gravity and can
    die. It has four Animations: moving left, moving right,
    dying on the left, and dying on the right.
public abstract class Creature extends Sprite {
        Amount of time to go from STATE_DYING to STATE_DEAD.
    private static final int DIE_TIME = 1000;
    public static final int STATE_NORMAL = 0;
    public static final int STATE_DYING = 1;
    public static final int STATE_DEAD = 2;
    private Animation left;
    private Animation right;
    private Animation deadLeft;
    private Animation deadRight;
    private int state;
    private long stateTime;
        Creates a new Creature with the specified Animations.
    public Creature(Animation left, Animation right,
        Animation deadLeft, Animation deadRight)
        super(right);
        this.left = left;
        this.right = right;
        this.deadLeft = deadLeft;
        this.deadRight = deadRight;
        state = STATE_NORMAL;
    public Object clone() {
        // use reflection to create the correct subclass
        Constructor constructor = getClass().getConstructors()[0];
        try {
            return constructor.newInstance(new Object[] {
                (Animation)left.clone(),
                (Animation)right.clone(),
                (Animation)deadLeft.clone(),
                (Animation)deadRight.clone()
        catch (Exception ex) {
            // should never happen
            ex.printStackTrace();
            return null;
        Gets the maximum speed of this Creature.
    public float getMaxSpeed() {
        return 0;
        Wakes up the creature when the Creature first appears
        on screen. Normally, the creature starts moving left.
    public void wakeUp() {
        if (getState() == STATE_NORMAL && getVelocityX() == 0) {
            setVelocityX(-getMaxSpeed());
        Gets the state of this Creature. The state is either
        STATE_NORMAL, STATE_DYING, or STATE_DEAD.
    public int getState() {
        return state;
        Sets the state of this Creature to STATE_NORMAL,
        STATE_DYING, or STATE_DEAD.
    public void setState(int state) {
        if (this.state != state) {
            this.state = state;
            stateTime = 0;
            if (state == STATE_DYING) {
                setVelocityX(0);
                setVelocityY(0);
        Checks if this creature is alive.
    public boolean isAlive() {
        return (state == STATE_NORMAL);
        Checks if this creature is flying.
    public boolean isFlying() {
        return false;
        Called before update() if the creature collided with a
        tile horizontally.
    public void collideHorizontal() {
        setVelocityX(-getVelocityX());
        Called before update() if the creature collided with a
        tile vertically.
    public void collideVertical() {
        setVelocityY(0);
        Updates the animaton for this creature.
    public void update(long elapsedTime) {
        // select the correct Animation
        Animation newAnim = anim;
        if (getVelocityX() < 0) {
            newAnim = left;
        else if (getVelocityX() > 0) {
            newAnim = right;
        if (state == STATE_DYING && newAnim == left) {
            newAnim = deadLeft;
        else if (state == STATE_DYING && newAnim == right) {
            newAnim = deadRight;
        // update the Animation
        if (anim != newAnim) {
            anim = newAnim;
            anim.start();
        else {
            anim.update(elapsedTime);
        // update to "dead" state
        stateTime += elapsedTime;
        if (state == STATE_DYING && stateTime >= DIE_TIME) {
            setState(STATE_DEAD);
}Any advice? Is it "protected"? Is the code out-of-date?
thankyou,
Lance 28

Answer 1

Lance28 wrote:
Any advice? Is it "protected"? Is the code out-of-date?Welcome to the wonderful world of Cloneable. In answer to your first question: Object's clone() method is protected.
A quote from Josh Bloch's "Effective Java" (Item 10):
"A class that implements Cloneable is expected to provide a properly functioning public clone() method. It is not, in general, possible to do so unless +all+ of the class's superclasses provide a well-behaved clone implementation, whether public or protected."
One way to check that would be to see if super.clone() works. Their method uses reflection to try and construct a valid Creature, but it relies on Animation's clone() method, which itself may be faulty. Bloch suggests the following pattern:public Object clone() throws CloneNotSupportedException {
   ThisClass copy = (ThisClass) super.clone();
   // do any additional initialization required...
   return copy
if that doesn't work, you +may+ be out of luck.
Another thing to note is that Object's clone() method returns a +shallow+ copy of the original object. If it contains any data structures (eg, Collections or arrays) that point to other objects, you may find that your cloned object is now sharing those with the original.
Good luck.