public void run(){
		while(this.status == Bullet.ALIVE){
			try {
				Thread.sleep(Constant.bullet_sleep_time);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			
			if( Game.status == Game.STATUS_ON){//judge the status
				if(judgeIfIn()){
					
					if( this.status == Bullet.ALIVE){	
						this.move();
						ifHitSomething();
					}
				}else{
					this.setStatus(Bullet.DEAD);
					break ;
				}
			}
		}
	}