java - Why won't my rocket lives decrease upon collision? -

ok, in game design class using greenfoot create game. asked make hardest asteroid game while making fair. decided add set amount of rocket lives. got set , works, never decrements rocket lives, how do it?

here code:

import greenfoot.*;  // (world, actor, greenfootimage, , greenfoot) import java.util.list;  /**  * rocket can controlled arrowkeys: up, left, right.  * gun fired hitting 'space' key.  *   * @author poul henriksen  * @author michael kölling  *   * @version 2.0  */ public class rocket extends mover {     private int gunreloadtime;              // minimum delay between firing gun.     private int reloaddelaycount;           // how long ago fired gun last time.     private vector acceleration;            // vector used accelerate when using booster.     private vector deacceleration;     private int shotsfired;                 // number of shots fired.     private int rocketlives;     private int collisiondamage = 999;      private greenfootimage rocket = new greenfootimage("rocket.png");     private greenfootimage rocketwiththrust = new greenfootimage("rocketwiththrust.png");      /**      * initialise rocket.      */     public rocket()     {         gunreloadtime = 10;         reloaddelaycount = 0;         acceleration = new vector(0, 0.035);    // used accelerate when thrust on         deacceleration = new vector(0, -0.035);         increasespeed(new vector(13, 0.3));   // drifting         shotsfired = 0;         rocketlives = 3;     }      /**      * rocket's gotta do. (which is: flying about, , turning,      * accelerating , shooting when right keys pressed.)      */     public void act()     {         if (rocketlives == 0)         {             getworld().removeobjects(getworld().getobjects(null));             greenfoot.stop();         }         else         {              move();              checkkeys();              checkcollision();              reloaddelaycount++;         }     }      /**      * return number of shots fired rocket.      */     public int getshotsfired()     {         return shotsfired;     }      /**      * set time needed re-loading rocket's gun. shorter time is,      * faster rocket can fire. (initial) standard time 20.      */     public void setgunreloadtime(int reloadtime)     {         gunreloadtime = reloadtime;     }      /**      * check whether colliding asteroid.      */     private void checkcollision()      {         asteroid asteroid = (asteroid) getoneintersectingobject(asteroid.class);         if (asteroid != null)         {             getworld().addobject(new explosion(), getx(), gety());             getworld().addobject(new rocket(), (1350/2)-20, 1000/2);             if(istouching(asteroid.class)) {                 asteroid.hit(999);             }             getworld().removeobject(this);             rocketlives--;         }     }      /**      * check whether there key pressed , react them.      */     private void checkkeys()      {         ignite(greenfoot.iskeydown("w"));          if(greenfoot.iskeydown("s")) {             deignite(greenfoot.iskeydown("s"));         }         if(greenfoot.iskeydown("a")) {             turn(-5);         }                 if(greenfoot.iskeydown("d")) {             turn(5);         }         if(greenfoot.iskeydown("space")) {             fire();         }         if(greenfoot.iskeydown("shift")) {             int ran1 = (int)(math.random()*1350);             int ran2 = (int)(math.random()*1000);             getworld().addobject(new asteroid(), ran1, ran2);         }     }      /**      * should rocket ignited?      */     private void ignite(boolean boosteron)      {         if (boosteron) {             setimage(rocketwiththrust);             acceleration.setdirection(getrotation());             increasespeed(acceleration);         }         else {             setimage(rocket);                 }     }      private void deignite(boolean boosteron)      {         if (boosteron) {             setimage(rocketwiththrust);             deacceleration.setdirection(getrotation());             increasespeed(deacceleration);         }         else {             setimage(rocket);                 }     }      /**      * fire bullet if gun ready.      */     private void fire()      {         if (reloaddelaycount >= gunreloadtime) {             bullet b = new bullet(getmovement().copy(), getrotation());             getworld().addobject(b, getx(), gety());             b.move();             shotsfired++;             reloaddelaycount = 0;   // time since last shot fired         }     } } 

i think saw error (debugging should show well):

it's following part in checkcollision():

getworld().addobject(new rocket(), (1350/2)-20, 1000/2); //here if(istouching(asteroid.class)) {   asteroid.hit(999); } getworld().removeobject(this); //and here 

on collision add new rocket world (which initialized 3 lives) , remove current one. have rocket 3 lives. reuse current rocket until dies.